If I paid for an app and I delete it because it takes too much memory space (I only got the 16 GB model) can I bring it back without paying again. Also can we put them in the Cloud to save memory space and bring them back when needed?
Yes, your app purchases are linked to your BBID and can be re-installed on any compatible device with that BBID.
Something I have always wondered is if the deleted app was updated to a new version after the deletion, which version is restored - the original installed version or the new version?
What I have noticed though is if you buy an app (perhaps on sale) and then delete it, you are not able to simply restore if the price of the app has gone up even if it is the same version.