Backing up my PS3 onto a Flash Card (downgrading my HDD)

[MarioMark]

I currently have a 1TB hard drive in my PS3 which isn't really being used as it's only at 20%, so I'm going to put it in my PS4 and put the PS4 500GB in the PS3 as the PS3 probably won't be being used as much after, and at least this way my PS4 will be a little more future proof without any expense.

I'm basically looking for the safest easy option and to use my 4gb flash USB stick for backing up precious data. Is there a way to move my accounts to the memory card and when my PS3 is running with the 500GB hard drive to move the accounts back and to then download my save files from the PS+ server? I won't need to do any deactivating/reactivating and all that, right?

Thanks in advance.

[MarioMark]

I've sorted this now. I'm just going to throw all my game saves in my PS+ online storage folder and redownload when I'm set up.