Population is tax payers.

Morale/approval affects population growth.  100% morale grows pop fastest, but there are discrete breakpoints.  I think something like 72% is the next one.  You can google galciv2 and wiki and get a ton of info there.

Basically, try converting your miner to a colony ship and then settling two good planets (NOT the other one in your home system).  Don't build hardly anything on the two new planets until their population grows enough to produce a positive cash flow. If there is a great research or manufacturing bonus tile, it might be worth an exception.  Essentially all buildings have a per turn maintenance cost, so choose the first buildings carefully.

Concentrate on research for the first ten or so turns.  Grab the first few bonus techs that give Empire-wide bonuses.  Yoy will have those all game, but only after you research them.  Depending on your style, you might research also the first Morale/Approval bonus, and/or go for the Economic Capital.  Trade "trade" with the first folk you meet to let them build freighters to come to you.  Consider researching the translater bonus tech.

Once you get most of those early techs, start building colony ships, especially when your home planet nears its maximum population.

You start with 5000 BCs.  Expect them to slowly drop.  Don't be surprised if you need to throttle down from 100% production at some later point until you turn the corner. 

You do not need to have karma to give it.

The market buildings do indeed affect only the planet thay are on.  Thus, they only help much on planets with considerable population.

On colonies and cash flow, go to the spreadsheet page for colonies.  You can see right there in one place which ones have reached a positive cash flow.  That is the signal to start more and more buildings there.  I often do not wait for a positive one, just for the negative number to become small.  Oh, BTW, don't forget to land and re-take off the colony ship on the first turn.  It starts with 100 pop but can hold 250 and you want those extra folk aboard!

In general, do not build farms on farm bonus squares.  That will not add to growth rate, but it will increase the max population on that planet.  The problem is that morale/approval goes DOWN as pop goes up, other things being equal.  Higher PQ planets (above 11) will have a higher morale/approval than smaller ones with the same pop.  There are exceptions to the no farms on farm bonus squares rule, but generally don't do it (one exception is the Economic Capital planet).   If you do, plan on building at least one morale bonus building there, and maybe two.  Note the bonuses also of the Political Capital.

Most experienced players convert the mining ship to a colony ship on the first turn, or as soon as they get a better engine tech (for more speed or range).  I think you just click on the ship (right or left) and get details, and you will see an upgrade button with choices and costs.  Once you design a ship, that name will be added to upgrade choices.  If yoiu can't decipher my ramble here on this point, post again here and I'll fire up the game and give you better instructions (I'm a tad hazy remembering the exact button specifics).

You will need to do a Colony Rush, and suffer the cash flow hit.  You just have to time it a bit more or be more selective on which ones you first colonize.  Also, you can colonize one planet, build a shipyard there, and then use it to build cheap zero engine colony ships on tiny or small hulls ans use them to colonize the other planets in the system.

One last point is to research sensors.  Putting sensors and Impulse engines on a merchant hull will let you build fairly fast and long ranged survey ships to grab the anomalies, many of which are BCs.  Many a time has a 1000 BC anomaly given me a bit of breathing room early.  I generally keep three survey ships operating, and sometimes more.  They also help speed finding minor races.  Remember to trade them Trade for something good so that they can send you freighters.

Thanx, and YAQW!

The +hitpoint anomalies, I have found, are generally worthless.  After the early game, even a flagship that has spent all game surveying has fewer HP than one of the larger ships.  Sometimes, just for grins, I design a real massive upgraded medium hull (same as the flagship) and convert it at huge cost just to mess around.

I recommend using only freighter hulls for survey ships and pack on engines and range extending modules.  In higher difficulty games, the pace really picks up, and your survival windows become small.  That is, you need to Colony Rush sooner, get higher research done quicker, and be ready to fight earlier.  Meanwhile, you have to build more sooner, get Constructors to mining anomalies faster, etc.  The money anomalies and early Trade routes with minor races become critical factors, thus faster and farther ranging survey ships are essential.

I recommend always picking race things to increase cash flow.  That is, I max out the economic bonus first, before I put race points in anything else.  Luck is good, and note that the Universal political party adds another 25% Luck.

On Farms and Bonus Tiles, if you get a real high PQ planet (say 20+), putting a farm on a bonus tile is probably fine.  The higher PQ planets provide a player choices.  That is, do I fill it with factories to pump out ships?  Do I fill it with labs and then put my Research Capital there?  Or, do I build some farms, a morale building or three, and fill it with Stock Markets?  The higher PQ planets have inherent Morale bonuses, also.

I use a slightly different strategy that you might find useful if you find yourself playing on a bigger map with more planets: rather than waiting until my colonies are able to support themselves through taxpayer money, I rush-research universal translators -> trade to get access to the economic capital.

I then set up a specialized economy planet - no starport, no labs, nothing except economic buildings, an economic capital, possibly a farm or two, and a morale building or two. I also set production focus to 'social' and start by build one or two factories to make the rest of the process run smoothly. I find that choosing a good suitable planet to be economic capital ensures that (early-game at least) that planet is able to pay for my entire empire despite most other colonies operating at a significant loss.

The most obvious choice for econ capital is my homeworld, since it has a high population cap and a large taxable populace already in place. Towards the end of the colony rush phase I make sure I have another world that has a starport and decent amount of factories, and then I slowly convert all the factories/labs on my homeworld to econ buildings.

Alternatively, if I find a really high-class (think 16+) planet with morale/food bonus tiles nearby, I make that my economic capital. It starts out with a low population obviously, so while I'm building the first improvements there, I also start to construct specialized colony ships on my homeworld (1-2 should be enough) with the express purpose of ferrying people back and forth to that new capital. If it's nearby, I sacrifice range for space, and cram as many colonists as possible onto one ship. Pretty soon I'd have a great planet with a maxed population and insanely high tax revenue.

Hope that helps!

That's about right I think... econ starbases also get modules that increase military/social production and research output, so they are very useful next to manufacturing and research planets as well.

If you're at war/on the brink of war, I would always build a recruiting center + farm on planets on my border; makes my worlds a lot tougher to invade

Regarding planet quality, high-quality planets are very rare but they do exist. I usually play on the 'huge' size map (reasonably large, and I can still micromanage my empire without slowing the game to a crawl) and each time I play I usually find 1-2 planets with a PQ above 20 over the whole galaxy. Just on my most recent game I found a planet in my adjacent solar system with a base-PQ of 24, and went on to win quite comfortably.