Slow Stick
Your 1100 mah battery pack will not hurt the motor.
I would recommend either of these packs for the way I prefer to fly:
7 cell 600AE Nicd
8 cell KAN950 Nimh
Yes, the Slow Stick can carry payloads. I purchased mine to do aerial photos with. I have not gathered all the info necessary to know what is needed yet. I do know there is obviously a camera needed and a component to go from the camera to the receiver.
As far as the obstical course goes. I've not heard of anyone doing that. But, I think thats a great idea and it sounds like fun. Are you planning on getting more than one Slow Stick involved, or would you be racing against the clock?