As an IT guy, NO RAID 5. RAID 5 sucks and you can end up losing a whole array along with all its data with it's crazy rebuilding. Either RAID 1 or RAID 10 if you are going RAID. You can also do backups to a larger HDD instead of going RAID.
Looking at your computer needs, it doesn't seem like you need a whole bunch and your shopping list looks good. Probably won't notice a difference in RAM 4x4 or 2x8.