re mixer (and vcas) always get more channels than you think you want right now - you will almost definitely need more in the future!
just looked at the revised rack - too many 'feature' modules not enough support modules (common noob mistake)
for a 6u rack maybe 2 or 3 voices at most - as you have other external voices - I would reduce this further (only 1 or 2) the interesting stuff most of the time is not the sound sources themselves, but but what you do with them
go and read a load of other noob needs help with 1st rack posts - you will see the same thing time and time again...
"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