Your Ride: 92 525, 88 325 hardtop'ed vert and 83 320iS
I hope your only doing the smaller lower oil pan where the drain plug is located.
If you want to use rtv it wont hurt anything, just apply a thin coat along the whole gasket.
Yes you can use ramps
Loctite really isnt needed but blue would work just fine.
Again blue would work, your engine isnt the one that has the oil pump bolts that back out. That was the e34 and e32 v8's.
1992 525i, 1988 Hardtop'ed Vert and 1983 320iS