I have some changes commited a few commits back in my svn repository. Let's say HEAD is at r750 and I want to revert r745 without losing r746-r750. Is this possible?
And, can I somehow save r745 and reapply it later (as a new revision)?
Supposing you get a clean backwards merge, you could do this...
svn merge -r 745:744 <source>
Then when you want to re-apply it, you could forward merge it back in:
svn merge --ignore-ancestry -r 744:745 <source>
For more info, check out the "Common Use-Cases for Merging."