1. 5%
2. 180 mo (rate stays same)
3. Found our own, 4.9% or something
4. 1% of take home was our max for everything (payments, ins, storage)
We bought the trailer to do monthly trips with, and were doing OK with that. We took the long term loan so that we could cut back on payments when the pinch hits, otherwise we overpay like it's a shorter loan. This came in handy last December when DW had to quit working to take care of our special needs DS. Our trips have cut back quite a bit, but we still enjoy the times we go, which makes it worth it.
As far as only paying cash for things... Oh well. I think it has more to do with how comfortable you are with your debts than anything.