Yes and yes.
1. There is a caveat to the ‘yes.’ The supervisor (or next approver) should be able to approve things “below” them – natively to NS, that is. I’m not totally sure of specifics, but I think you would have to make your own notion of “approver” or “next approver” to set that next person to after a period of time. Beware of domino effect of changes required if you choose to use a custom “approver” notion. Since I built my big approval workflow a couple years ago, I’m sure there are some changes to SuiteFlow that make this stuff easier.
2. You could do this through a saved search. I’ve done it with a workflow action that executed every day at same time and stayed in that state, reminding the currently required approver, until the request was fully approved.