There are no drain holes on the bottom. There is a nut on the bottom of each one that holds the internals in place. Don't undo that nut unless you plan on rebuilding them and have all the necessary seals and fiber washers on hand. Likewise if you pull the too large nuts holding the fork legs onto the triple tree hold the forks upright while doing so or all the oil will spill out.
As to what else they will fit: any Puch moped and I'm probably not many other mopeds without modification. However size wise they are much longer than maxi/newport forks so really to answer your question they will fit on a Puch magnum.