I forgot to mention this earlier, FF is defenitely the goal so i would want to invest "right".
If you don't mind I am saying this but you are going the wrong way - instead of buying the D7100 why don't you buy a D750 or if it is too much buy a D610 and get a 24-85VR
Financially it is very much on the ball park - prices are based on Amazone.com and rounded off to the nearest 100.
D610: $1500 + 24-85: $600 = $2,100
D750: $2300 + 24-85:$600 = $2,900
D7100: $1000 + 24-70: $1,900 = $2,900
D750+24-120 F4 VR= $3000
So instead of going the DX way you may as well get the FX body and be done with - 24-85 is a decent street photo lens - or if you can stress a little bit more get the D750+24-120 combo this will last you a long time.