Savage X SS 4.6 Kit Question
 

I just sold one of my airplanes. I have the RTR Savage X but the motor is shot after about 8 gallons through her. After looking at the price of the upgrades to make it an SS and a new engine I think I'm better off just getting the new 4.6 kit and swap my electrics and have spare parts. I have a nice track in the back yard with a table top about 4 feet tall and 6 feet across, a set of doubles, and a set of triples. I do beat on my trucks "a little".

Question #1 Are the diffs assembled? Or do I need Diff grease and what weight do ya'll suggest Front & rear?

Question #2 Shock oil does it come with it or do I need to buy it and what weight do ya'll suggest?

Question #3 I have a RR steal spur and clutch bell. Should I use it or the one in the kit?
And will the RR clutch bell mesh with the HPI steal spur gear?

Question #4 Are the tires any good (balloning or swaying like the crap stock tires)? I've been running stock Revo tires and was wanting NUBZ. I have a friend that comes over and he has some Revo tires that look like bowties and they hook-up on my track.

Thanks for any help,
Brian