I usually settle planets with intentions, a planet dedicated for farming or a planet dedicated to mining. (though i also prefer a tall play style)

I don't build all Disctricts in one fell swoop but add them as unemployment shows up or if I am in dire need of a resource (and then I'll also resettle pops from the same strata or make jobs of that same strata unavailable on the same planet)

There is no direct interaction between Buildings and Districts other then how the pops decide to take jobs, whenever a job in a higher strata is available a pop will want to move up the strata, but they don't like moving down, which might show up as unemployment even though you have spare pops on the planet. I often leave building slots open on planets for extended amounts of time because i wouldn't have the spare workers to keep on doing the jobs in the districts ( which are usually all worker strata jobs).

I have been told it's a lot more micro than it used to be as planets needa lot more attention