Most use RTV(silicone) on oil pan gaskets, which is fine, just don't overdue it, when you tighten up the pan the silicone will squeeze out INSIDE the oil pan, and when it drys can fall off and plug up the pick up screen
Seen it alot in older engines after previous owners tried temp fixes to fix leaks, loosened the oil pan a bit and pumped in the RTV, then tightened it back up.
It is good to use some as it seals uneven spots and holds gaskets in place, more is not better in this case.
Cork gaskets are better for oil pan and valve cover gaskets, over time they swell from contact with oil, making them seal better
Rubber gaskets are used when you will be pulling valve covers off and putting them back on several times, because that can be reused.
Oil pan and valve cover areas should have NEGATIVE pressure inside when engine is running, thats what the PCV valve and PCV system is for.
So if your PCV Valve gets clogged up it can cause oil leaks, so good reason to check it and change it every few years
While any engine is out its good to replace the rear main seal, its a cheap part(maybe $10) but hard to get at if it starts to leak, have to pull transmission(or engine) to get to it