(1) clean all contacts from the battery to the bulkhead connector to the fuse box to the headlight switch to the dimmer/foot switch, to the headlight terminals with Deoxit cleaner.
(2) clean all engine wiring harness grounds.
(3) install a relay in the headlight circuit. Make the current headlight feed wire the + trigger for the relay.
(4) if adding the relay and clenaing all contacts and grounds doesn't get the lights bright enough for you, get a set of GE Nighthawk headlamps.
(5) if 1-4 doesn't get your headlights bright enough, contact Dan Stern at www.danielsternlighting.com
and order a set of Cibie conversion headlamps from him. Not cheap, but definitely the best headlamps you can get for your van. Mr. Stern also sells headlight relay kits and can walk you through installing them.
RE: making engine cover quieter:
Ram4Ever (I think it was him) did a great post a few years ago about removing the factory fiberglass insulation from the doghouse on his Dodge and rebuilding it with both new fiberglas and reflective insulation. It reduced engine noise and reduced heat transmission into the cabin. Shoot him a PM, or maybe he will poip in and offer his 2¢.