Sounds like you'll have the most versatile of all the characters on the board (aside from the conjurer, depending on what he wants to do with his character), and as such, you'll need to tailor your activities to the situation, the foes you face, and what everyone else tends to do.
You'll also want to tailor your soulmelds with this in mind, as well (or use them to save you on powers known/UPPD used, such as for flight, or grab things psionics just can't give you readily, such as the shoulders bind of the phase cloak for defensive and utilitarian ethereality).
I doubt you'll want to enter combat directly most times, since you've got plenty of combat-fodder already, so use your combat powers as strategically as you can. Things like time hop on enemy mounts, and to change terrain to your advantage (knock out a chain link of that chandelier to drop it on foes, or on the supports of a bridge), and on fallen foes and allies to keep them out of combat to prevent them from dying when you want to keep them up and running. Astral construct is an incredibly diverse power; everything from mobile soft cover to battlefield control to a disposable grappler to a trapspringer to a flanking buddy and more.
Basically, enable the group's strategic mindset through clever use of your powers, and you'll be amazed at how easily you can turn the tide of battle on your own.
Outside of a fight, you have six basic powers you'll default to: psionic charm, psionic minor creation, astral construct, time hop, wall of ectoplasm, and energy wall. These powers should cover 99% of everything you'll want to do out of combat, especially since they can do virtually anything between them. Just use your imagination, and it's astounding what you can pull off.
