I have used desktop manager to back up my 8830. First, I backed up to my laptop, then I backed everything up to my memory card on my 8830. My question is - Is there a way to restore my phone, if it crashes, if I don't have my laptop?

You will need to restore FROM the *.ipd file which you backed up. Where is it?

As an added measure of safety, I backed up to 2 locations:
1) to my laptop - I don't think there is a problem with restoring from this.
2) on my SD memory card in my 8830. Can I restore from this without using my laptop?

2) No. You must restore using Desktop Manager on the PC. Since the BB might not be readable should you get in a need-to-restore situation, I would not depend on the Media Card being accessible.