Be warned, there's a fair few assumptions in what I'm about to write.
The spell gives you a CMB to use, CL + casting ability score. You probably can't add to it with feats but it's not clear.
The spell doesn't say anything about your CMD so this is probably unchanged. Yes this makes polymorphing into something big make telekinetic grappling work better but I don't see a way around that. Assume that the extra mass helps anchor you in place maybe.
Dragging the enemy next to you seems unnecessary (and startling considering the potential range of telekinesis) but there's nothing clear about it. I wouldn't make this happen.
Reversing control of the grapple makes no sense at all IMO. Just don't allow it, there's nothing there to counter-grapple. Escaping OTOH should work just fine.
In the event that the target somehow wasn't able to escape on its turn you should be able to convert a grapple into a pin with a second successful check. Similarly tying them up after a pin. Moving the target would move just them IMO. Damaging them; eh, if you can't think of something better to do with a 5th level spell than unarmed damage 1/round, go for it.