Preface all the following with "as a noob I have found..." and take with the grain of salt that goes with that statement. I never build farms on the homeworld. 16B is plenty of people for a class 10 planet, even after terraforming raise it to a 12+. I mostly only build one farm on colonies (and well down the priority list and only if the PQ is high enough to leave some free tiles after the basics) then carefully let the one farm upgrade by researching more farm techs. But even then you have to watch out especially if you build farms on bonus tiles, it is okay to do just make sure you shut off the auto upgrades for that world (I think it is in the governor screen you select from the planet view) so when the advanced farm techs hit that world does not explode - gives you a bit more micrmanagment headache but worth it, same goes for advanced factories and labs, research the techs for the bonuses but unless you have bonus tiles under the buildings the low-tech buildings are better, just build more of them as you can afford it. Now, a class 20 planet okay you can let the pop go wild with a few (or a bonus) farms and still have tiles enough to build lots of entertainment and stock markets.
Hmmm... some good thoughts on tax rates and approval. After looking at the formulas (in the Wiki) it at first seemed like a good thing to be at 100% approval everywhere during the colony rush as the x2 is much better than the x1.25. But the issue is what that does to your tax rate and how long your money will last versus more taxes and less approval. If it takes 1.6x as long to build up your population base at sub-100 approval but you are able to rake in 3 or 4 or 5 times as much income then you have that much longer before the colonization hangover sets in and that extra time, even at a lower pop growth rate, leaves you in better shape.
So I will have to look again at the pop growth and approval and tax rate formulas and re-evaluate how I am doing this.
Thanks for pointing that out.
I wonder also, my homeworld obviously lags, a bit, behind in approval as the pop is slightly higher. Pop growth on your homeworld is a separate issue from pop growth on your colonies. For the one you just want to get your colonies to where they can be in the black when you start building on them, for the other you want to increase your tax base on the one world where you are actually making money. But I suspect growth on your home world might be less important, provided you keep it above 41% so it at least grows _some_.
So next game I try small hull no-engine no-support cheapo colonizers with setting my tax to put my homeworld (and hence every world) at or above 41% approval while setting production at 100% until the money runs out, but only building on my homeworld, and even on my homeworld only the necessities like two factories and a lab (especially any homeworld bonus tiles) so as to focus on cheapo colony ship building mostly, maybe a bit later also some entertainment to bring approval up to where my colonies are so I can tax more across the board. See how that works.