The sample format is still the same, so sample files should still work in current MAME. I can't think of anything added that might not be part of the MAME download, so you should be complete. Other support files, you'll need to visit other pages for. Your 57gb total sounds like you have "Split...

I've been out of Mame for many years, since pre .100 romset.. So many things have changed.. I have 57gb .177 romset ( I believe that's unmerged or split.. Not sure how to tell ) and .177 (414gb) CHD's. I also have a samples folder from .162 as well as artwork from .162.. I've hunted high and low but...