Multimeter:

If a standard fluke multimeter will work, then one from Radio Shack 
should too.  I don't recall the description of this specific multimeter, 
but the Bently books generally seem to call out measurements that are 
within the capabilities of any cheap multimeter.

Drain Plug:

Is this the same size plug used on the Beetle?  If so, the cheap, large 
allen sold by VW shops should work.

Bill