The big parts cost the most to crate: you could leave big parts uncrated and have smaller ones crated, then convert the crates to shelving / storage in your work area. 25 x 25 is pretty good space if you store parts along edges, but until the wings/fuse are mated they'll take up a lot of floor space. I have moved large assemblies back and forth from storage as completed. Wing rack (EAA style) is very convenient for storing wings as previously mentioned.
As far as finding parts goes, that is a challenge - mostly with small parts in bags. No perfect system here since so many of these are "one off" sets or type of parts (specialized screws, brackets etc). I always separate common rivet types into their own storage areas since these are "generic" and usually in large quantity (But it's also common to get duplicate sets of same size rivets in different bags, that's Van's system of matching bags to assemblies).
If I were storing "bag parts" other than common rivet types again, I'd separate common types (AN bolts, screws, washers, nuts, cotter pins, etc etc) into generic groupings in storage boxes or bins, and leave only the unique/one off parts in bags. I'd put the bags in one place, with large labels on each bag. FYI - this spreadsheet really helps when searching for an individual part:https://docs.google.com/spreadsheets...it?usp=sharing
(shared by HeliCooper who also has the annotated plans wiki).
One thing I also did which seemed to work well was keep "subkits" together until they were down to just a handful of parts. Another approach to subkits which would take a lot of time up front but save a lot on the back end would be to separate them by section (like section 29, 30 etc) and put parts for each section together. Some sections would be huge piles of parts though!