regarding the vibration issue i think your cars drive axle is vibrating on load, this is because of in board CV joint. Check out my earlier post regarding the spiders & rollers of inboard CV. Also check out the tip regrading the proper grease for inboard joint by Mr. Xulfiqar.
You need a good suspension guy, who will
1. repair or replace your inboard CV joint,
2. check and replace if necessary khich, chimta bushes,
3. take out the kangi, service & grease it. check & repair or replace the ball joint or ends. If the teeth of kangi are ok (they get wide creating play) no need to change it. replace kangi boots (KS rubber boots are good)
The gear oil is leaking from the axle seals, replace both (one will be big and other one will be smaller). the trick is in fitting the seals otherwise they will leak again immediately. in case of over filling,Check the speedometer cable assembly fitting on top of the gear box for leakage.
The oil on the silencer (front dohlki) is probably grease leaking from cracked CV boot coz its very rare that gear oil from axle seal falls on the silencer.
Why is that you are saying that wheel bearings need replacement, do you hear an echo (goonj) which increases with speed or any dhak dhak sound while stopping or moving from stand still?
What about the tyres (condition) and their balance?
