Are cameras permitted in Disney World?
I like to take pictures with my SLR & video camera but I also like to go on roller coaster and water rides.
Are there places to store belongings (ie. daypack) nearby so we can go on the rides? (Although it would be kinda cool to videotape my rollercoaster ride!)

Of course you can bring cameras. They have lockers all over the park for long term storage, but most rides have ample space for a backpack.

Can we bring cameras on rollercoasters?
Is there ample space for that?

Go to your local camera shop - not the one in the mall. They will have a selection of camera fanny packs. The camera fanny packs are padded like a regular camera bag. I am assuming you have a small 8mm or digital video camera. Take both the SLR and video with you to the store - if you plan on taking both into Disney at the same time. Try on the fanny packs and with packing the cameras in them. What you choose should be one that is easy to quickly get out and put up the camera of your choice. Also make sure it has just a little extra room for sunglasses, tiny bag, etc.

DW may be different, but many parks won't permit cameras on rollercoasters. Not sure why, but am guessing it's because too many people drop them -- and expect an easy retrieval.

Just remember that it's always best to travel light and carry as little as possible.
It's no fun being overwhelmed by your bags.
Also, all bags are now subject to search (9/11).
Have fun!

There are not that many roller coaster at WDW. Just Space Mountain and Thunder Mountain in the Magic Kingdom. Then you have the Rock N Roller coaster in MGM. If you want some great coasters in Orlando, go to Islands of Adventure.