Canon Powershot A75

Right now, I'm using a Canon Powershot A75.

I haven't been having the best results with it, but it still seems like it could do a better job. My goal is to be able to get good quality 8x10's out of this camera.

I'm looking for a telephoto lense for my camera - where would I be able to get a deal on one? Do they make them "strong" enough to zoom to get a good shot of a plane taking off from Plainview Park?

Does anyone have some tips/tricks on using this camera?

Here are some photos that I have taken with this camera. Some turn out good, others don't.

http://i6.photobucket.com/albums/y22...n/IMG_1630.jpg
http://i6.photobucket.com/albums/y227/CDolan/af1.jpg
http://i6.photobucket.com/albums/y22...n/VH3DKAVP.jpg
http://i6.photobucket.com/albums/y22...n/IMG_0499.jpg
http://i6.photobucket.com/albums/y22...n/IMG_0490.jpg

Any help would be appreciated!

Also, about 2 months ago, my camera fell off my desk, onto my computer hard drive tower. Because of it's fall, it now has a dent in the casing to the right of the viewfinder. Would this have caused any damage to the sensor? Is there any way to check for damage?