Aside from my transmission taking 2-3 secs to engage into reverse I also began experiencing loud humming sound when going over 60+ mph. my tires are less than 10k miles - bridgestone potenza poleposition tires. done an alignment roughly 6-8 months ago. i have 51k miles on the car.

Read some where that my bearings needs to be replaced, but would like some opinions here before I do so. anyone have an idea what needs to be fixed? what's the ballpark range should I expect to pay?

 

Several things can cause that noise - support bearing on the drive shaft, wheel bearings, transfercase (if x-drive), differential, transmission itself. You will need to diagnose further to rule out some of those. Good luck!