I don't know if you can relaunch with Jam Session. You can with Dark Hole, and they have similar hitstun. You can break 800k for 1 bar without assists regardless.
You can't relaunch after an air combo with jam session, no. You CAN do it after a throw in the corner, though.
Jam session's best assist extension is,
blah blah air combo -> TK L RP -> Hard Drive, cM -> sS + Call Jam -> sjM, delay, sjS, land, L RP xx Dome.
Otherwise you're best off calling it right before RP xx Dome, or not calling it at all(because you want it for the incoming).
Alternatively, if you have your dante assist available, and haven't used your groundbounce via jS, you can do
TAC Up to Dante -> jMH xx Airplay, jM double jump jMHS, land, Volcano xx Beehive, Stinger+Call Drones xx BC Revolver, jump, skydance, beehive, Stinger xx BC Volcano xx Beehive xx Million Dollars xx Dome
to build a lot of meter and do very good two bar damage, but that's only if your sentinel is dry on meter, etc.
Truthfully, Jam is so good for Sentinel in the neutral, though, that more often than not you won't have it available as an extension because it'll have been used in the neutral leading up to the confirm.
Plasma Beam vs Missiles is a tough call for Sentinel, IMO. Missiles greatly aids his lame game, and Plasma Beam aids his aggressive game. Dios tends to use Missiles, IIRC, because he plays a very lame style sentinel. RayRay plays a very aggressive style Sentinel, and would definitely prefer Beam(or Disuptor, in similar usage from Magneto).
Can someone give me some tips on how to setup grapple resets better? I can't seem to get it after Stinger consistently.
My advice on how to learn grapple resets:
Do a wiff sH, then cancel it into BC Hysteric. This motion is difficult, because you have to combine the BC with the QCF in a small window(prejump frames for BC are 3 frames, IIRC?). You want to see Atk+S, and 236+H, in the input display, and you want to see Dante do sH xx Hysteric.
Once you can do THAT, you can do grapple resets. Just do the stinger wallbounce, wait a tiny bit, and do that same motion(minus the initial sH, of course), and you'll get your BC Hysteric. Press H again for Grapple.
Trying to combine the whole thing into one clump, instead of just trying to learn raw BC Hysteric, makes it more difficult IMO. Then you have to avoid crossups, accidental Jam Sessions, etc.
I'll continue practicing for sure. 
