Kosmos3D made a couple of little plugins that can convert basic corona material back to c4d standard:
https://www.kosmos3d.it/coronatoc4d/
it can't do complex shader setup, so I usually tweaks things manually in the corona node editor, but it gets you more than halfway there.
also vraytoc4d:
https://kosmos3d.gumroad.com/l/pgZTY
for the default render settings, save a "new.c4d" in your app folder which has the settings you want, and that will get used as your default startup scene.
