Yea, I was going broke and I didn't have any military. I was also playing on the smallest map, which made it a bit more difficult.
Different map sizes just lend themselves to different play styles. One is not necessarily easier or harder.
The mistake I was making, was building only one econ building.
It is easy to overspend in GalCiv2, under any version. Money is the most important thing in this game - it lets you do everything else, although that is often not clear right away. Econ buildings help a lot, so does researching better government styles, as well as taking econ bonuses and morale bonuses from the getgo.
Whats generally a good fac/eco/lab ratio on an average planet, say, PQ 10?
Broadly speaking it is better to speciliaze your planets.... a planet with all labs will benefit more from econ starbases and the technology capital than one with a mix. Still, depending on how many planets you own, you may have to mix it up a bit. Even when mixing it up, I would suggest going labs/econ with some worlds and factories/econ with others, and then some worlds (if you can spare any) that are ALL econ.
On the game I'm playing right now, I'm doing 1 farm per planet.
That is fine, as long as you never use a +300% farm tile or put any farms on planets that start out with a pop capacity of 16 billion, only on the planets that start with 6 billion. If you only use one farm per planet then you are free to research up to the end of the farm line whenever you need more people.
Should Happiness buildings be used? I'm finding it my taxes are too high, some planets approval will just continually fall.
You should not use happiness buildings. I have a thread elsewhere with lots of math, but in almost all cases happiness buildings lose you money rather than gaining it. More econ buildings is what you want, and your tax rate should be based off of the happiness you get from morale bonuses that apply empire wide. Things like mining morale resources, the morale ability points you spent, the morale bonuses from researching the entertainment tech tree, and the morale trade goods. In short, 1 farm + 2 stock markets makes almost twice as much money as 1 farm + 2 morale buildings and a higher tax rate. I won't bog you down with the behind the scenes math here.
IF you have a morale bonus tile (it looks like a blue water drop) then you do want to build the weakest morale building you have on it. Those tiles add a flat +100% to that planets morale, as long as ANY morale building is on it. Morale buildings don't do as much as they say they do (more math) but for instance, if a morale building SAYS it adds +10% it really adds between +6% and +2% for most populations. This is because there is a hidden penalty that was added over a year ago to penalize high population worlds, so the effect of morale buildings scales down the more people there are.
In short, focus more on making money. Better governments, happier overall people (not from buildings, from bonuses), and lots of econ buildings should help you.