lots of questions

[david_12121]

1: my front diff oil smells like sh#t...literally...are they all like that? (and the smell fills the cabin on hot afternoons)
2: how do I test for head gasket problems? (it does not overheat, no oil in coolant and vice versa, but exhaust smells weird)
3: AC has leak, no sign of oil on the hoses, will AC sealant fix these? should I try?
4: car runs rich in the mornings, has awful fuel economy, what could it be?
5: I once punched it in the freeway and it did not shift down, kept it floored for more than 10 secs and it did not shift down..finally put it on power and it shifted...anything wrong? (rebuilt tranny 3k miles ago)
6: is changing the spark plugs difficult? more than timing belt?
7: I found a post about putting a switch for 50/50 power distribution in the center diff on the 4eat's...possible on svxi?
8: (not svx related)has anyone ever tried this product called plasti-dip? any good?

sorry for asking so many but I assume they are all short answers so why not...please answer as many as you can