Diaper bag and supplies

I was going to use a backpack as a diaper bag, I am going to try Costco brand formula if that works out can I put scoops of formula in bottles without the water and just add water when it’s time to feed baby or put scoops in a plastic sandwich bag or plastic Tupperware or do I have to carry the whole container of formula around in the bag? Also, for outfits diapers and bottles should I put 2-3 outfits,and about 6-10 diapers for a whole days worth of supplies? And

Bottles I’m not sure how many to pack.