OM617 Intake/Exhaust Manifold Gasket Help

[MSGGrunt]

I searched, but clearly not well enough it seems.

I took off the intake/exhaust manifold as part of my turbo rebuild on my 1982 300SD and have a couple questions.

1. What gasket should I use? Erling? Victor Reinz? What is OEM?
2. Would copper spray hurt, help, or really not needed. I have read different opinions.
3. I know the torque specs for the intake nuts are elusive or even non existent but, people must be tightening them to some value? What should I tighten the nuts to?
4. Is it a good idea to replace the manifold studs and nuts or really not necessary?