Population and production

Pop and production aren't linked. Buildings have maintenance cost associated with them, so early in a planets development you want to avoid ploppong down a whole bunch of high maintenance buildings till you can get the planet making money. One way is to first build your early economy buildings. They don't have maintenance costs like most and will help the planet become profitable faster.

You are correct. Production is not dependent on population. So no they're not linked. But as far as not wanting new buildings on low pop worlds, I'm not sure where you got that idea.

You do want to be careful when colonizing a new planet not to overburden the planet with unused production buildings since they do require some support, but this is only a concern for recently colonized planets with pops of less than 1B.

What you may be talking about is how most people use PQ4's and PQ5's. It's mainly because you really can't put enough production on these planets to make them worthwhile ship producers that most people simply use these for research. However, a PQ5 with an initial colony, 3 factories and a Starport can do a decent job of producing constructors.

BTW nothing wrong with newbie questions.   

: how are production and population of a planet linked?

Production costs money, population makes money.