This looks like a fun starter list! It's unfortunate that you have such messed up models, but it could still be fun!
I would strongly suggest checking out some of that Tactics articles on here, Ragewind(i think) wrote a great article on each unit.
Tempest Launcher is the best weapon in Eldar for anti-MEQ - use crack shot with it, 2 blasts S4 AP3 ignore cover, AND reroll failed wounds. You can cripple any marine squad every turn, and let his fellow reapers clean up the mess. ALWAYS shoot with the Exarch first, so you hit more marines with the blasts ;).
Jetbikes are still troops, and I would maybe use the Falcon with Twin-linked Scatter lasers as another Wave serpent - it would make sense at least
Eldar are expected to have a new Codex in late 2013, so I would suggest buying things that are finecast, or finishing any units (like hawks, rangers, scorpions). Right now Eldar is not a very competitive army, so I would suggest taking things you like the looks of, or waiting until the new Codex comes out to expand
Things to buy now:
Fire Prisms - magnetize the weapons so you can use them as Nightspinners as well - I always magnetize everything (Wraithlord, Falcon, Wave Serpent, Warwalker, Vyper, Exarchs, etc.) so you can have multiple loadouts without having to buy 3 of the same model!