I have very little to no knowledge in doing a raid set up but I've recently decided think its probably the best idea that i do set up raid for my next pc because i will have projects and other files in general that are very important and i most not lose them.
before i state the question i will describe what i have, in my current pc 2x1tb, and both are almost full.
1st question: to do a raid 5 set up with 2 hdds do they have to be the exact same model or just two 1tbs hdds?
2nd question: if my two 1tbs are different hdds can i have 2 separate raid 5 set ups going if i bought a second hdd for each one so that ill have 4x1tb?
As Rogue77777 stated you need at least three drives for raid5. And to get a real advantage you should use a dedicated raid controller, not the raid function of your mobo. It's not easy to get a raid running, but it' way more complicate to get the data back, when it fails!
If you don't want to lose your data, a solid backup strategy is more important. Get one or two external drives and make redundant backups of your files. Or backup to a cloud service.