Kaffenback Build - Send help, it has strange things called gears!

I never actually thought of it like that, I always thought of it as just losing a whole set of important gears. When in actual fact, you're just losing a middle man between gears. Cheers for the insight! It doesnt seem too daunting now, just means stronger legs haha.

I can get 105 11 speed for a decent price, and I think i found that the medium cage rear derailleur is capable of doing the job, but do I need 11 speed? Is 10 speed better? (id have thought more gears the better?). If I went 1x up front, but used a 105 rear derailleur would there still be the possibility of getting a compact chainset somewhere along the line and being able to change out or is it all very brand/product line specific?

Im looking at options for 1x and the best is looking like sram rival I think, or at least the easiest for me to get my head around here. Just get the apex 1 chainset then rear derailuer and cassette and then good to go? As I cant find a 1x up front crankset from shimano. Or can other brands be use/any recommendations?

Im going to be using friction shifters, so really speaking compatibility with shifters isn't something I'm too bothered about. If I can get hold of a set cheap then I might be game for it, but I just see it as a more expensive option.

Cheers for all your input so far guys, and sorry about the silly questions. Still trying to get my head around this

EDIT

So I could really speaking mix and match to my liking? For instance, SRAM Rival 1 1x11 chainset, then just have a shimano 11 speed cassette and 105 derailleur and a sram chian and all would be fine and dandy no problems?