Hoooooooooo boy. I'm gonna get into big trouble here ...
Any information on OTV Support
Yes on OTV and LISP.
ISSU support (like NXOS)
I'm going to go vague here so you can "read between the lines".
1. IOS XE.
2 Sup2T (in a chassis) + Sup2T (in another chassis) = ????
Sup2T with 6700 line cards?
Yes and no. Some cards, like the 6708-10GB, won't be supported because of the DFC3 card is in-built. The rest of the cards will depend if you can or want to upgrade to DFC4.
Another thing, alot of your questions can be found here:
Catalyst 4900/ Catalyst 6500 Platform Update and Positioning
Start reading from page 18.