I want to build up a bike over the year, i want sram.

should i pick up the breaks for $80 and keep getting the group peice by peice, or save $ and just buy new group together? and if i get one rival component, do i have to "match" all other components with rival? or can i mix and match with force or possibly red.

also i dont plan on getting the frame untill i see "the one", are there any components i should wait on untill AFTER i get the frame (like the front derailleur due to diameter, or can i get braze on for anything)

also , i hate threads with out photos,