NP :-)
I think planning too much is a bit daft - the plans often change as soon as the first (group of) module(s) is/are bought!
Case is big enough - I guess its a b-company go - just watch out for power consumption especially the -ve rail - I have a mantis (which is what the b-company cloned the psu for the go from) but it is 30% smaller - I have issues with -ve rail consumption in it depending on modules (but I do have some really -ve rail hungry modules)
personally I'd just dive in with the minimum viable synth I suggested above (including the utilities) and have an idea of where you are heading (rough number of voices etc - so that when you come to expand you can for example get the right final stage mixer to start with)
the only thing I would think about long term is whether drums in the rack are a thing you need - or whether you'd be better off with a drum machine (or similar - I have a vermona drm1 mk2, I sometimes use) as they usually work out substantially cheaper (but saying that I also have percussion in the rack!)
in terms of how many voices I'd want in this size rack - drums plus 3-4, or 5 maybe 6 without drums - otherwise not enough space for everything else!
btw - for a tuner - there are lots of free phone apps!!
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities