The oil lines all have either O-rings or sealing washers (depending on which lines). If the lines are leaking and they aren't loose, then it's time to replace these.
The side covers & pan can be resealed with gaskets or RTV form-a-gasket products. The pan just unbolts right off, but be careful, several folks tearing into older/high mile motors have broken bolts taking them out, so penetrating oil may be a wise move before attempting removal. Be sure when you re-install that you tighten the bolts down in stages and do it evenly to keep from stressing/breaking the pan.
Your initial horrid noises could have come from a loose cam chain, but the tensioner finally kicked in and did it's job.
. . . that's what it sounds like from here anyway.
Is it possible the "loose parts" noise is the lash between the rockers and the valves? The B6/12 engine normally has a noisey valve train. A quiet one is an indication the lash is too tight. It should sound like a herd of mice with typewriters.