Lately I have been hearing this thumping noise when I drive down the road at a high speed and then stop accelerating. This happens only once in a while tho, but when I am driving very slow or not gassing it, I can hear this squealing noise coming from the middle of the car, and its close to a wobbling sometimes.

Could this be a sign of bad wheel bearings? My right long axel is also releasing a little bit of grease from the rubber boot. Any suggestions?

If the boot is leaking, you are going to need a new CV joint or at least replace the boot 1st chance and thoroughly clean/inspect the joint. regardless of whether that is causing the noise, however, I have found you need to fix the obvious problems 1st, then see if the others are still there. I am also a believer in buying NEW joints, I have never had any luck with the rebuilt ones lasting more than a few thousand miles.
Also, your symptoms sort of sound like a bad inner joint...

Try http://www.raxles.com they have a troubleshooting link describing various symptoms.

jack car upo, wobble wheel, if it shakes then bad bearing,if you hear crackling while turning its a bad axle or joint. try to torque all your lug nuts and see if it continues.

I went to the supension mechanic named Mike today and he took the celi out for a test drive. He says the wheel bearing has gone bad. I'll do the repairs tomorrow, but since I can't press on the bearing Im gonna go back to him and make him do it for me for a small fee.

I got myself a lifetime bearing, so it should last all my thrashing and hard cornering. I Might just have to replace the other 3 one day when they go out of commission.