If you search around these forums there is step by steps on how to do it.....some keywords for u:

tether
razr bluetooth
verizon tether

The problem u will have is the $15/mo plan i do not believe is a tethering plan which means that if you got caught you'd be looking at a pretty decent phone bill... the tether plans are usually more expensive.

On my blackberry if i receive a call it interrupts my bluetooth...so id say yes... but i dont know if the razr or some other phone has the capability of doing both.