I have 35d and don't have any buzzing or vibration from the engine.
From the outside the engine does have a slight distinct diesel sound but much softer than the traditional trucks. It is hardly noticeable between the petroleum engine and evn even less noticeable inside.

I think because of the adblue system in the back, there is no spare tire.
at less that is the case if you have a 3rd row seats. You should check with your dealer.

You can go non-RFT, lot of tire selection, check tirerack.com
Just carry tire sealant and a air compressor package(Green Slime sealant stuff).