precautions to take before upgrading iphone 4s to ios7 from ios6.

I've a jail broken iPhone 4s with ios6 and I want to upgrade it to ios7.

Pls do suggest me the precautions before and after upgrading.

Will I need to jailbreak ios7 again after upgrading?

And last q!

Can I take the entire ios6 backup to my pc before I proceed ?

Using that can I rollback to ios6 if required in future..????