Steven,

<< 1) Can I drive 5 miles to a shop beltless?  Certainly I can do without
     power steering or A/C, and I ought to be OK without the alternator
     for a while.  So, I suppose the only worry is the water pump?
     Can I run for 5 miles un-cooled on a cold day, if I watch my
     temperature gauge?  (Note: when my belts broke 7 months ago, I
     didn't realize it at first, and kept driving.  Within 5 minutes,
     the coolant distributer box had burst, necessitating a tow and yet
     another round of expensive repairs.  Obviously I don't want to
     repeat that, but it was in the middle of summer, and I wondered
     if that might make a difference).>>

ABSOLUTELY NOT. You will likely break the water T-pipe again if drive w/o the
water pump running. The alternator and the water pump share a belt. The other
stuff you can get away with.

<<(2) I think Wal-Mart carries temporary-use "emergency belts" that strap
     on easily.  Any thoughts about using one of those to get the van to a
shop?>>

Belts are relatively easy to replace. However, if you must use the temporary
belts, they should work if you are able to cinch it up to get the water pump
and alternator running. I have personally used a cable tie (a giant version
of those little plastic ties used for wiring and stuff) as a temporary belt.

<< Any ideas what would cause new belts to spontaneously break?>>

It is possible that the plastic shielding from the AC compressor slipped
under the belts and caused them to twist on each other. Tightening the belt
too much can cause this too.

Changing belts is as easy as loosening bolts. Slipping the old belt off. New
belt on. Put tension son the belt. Then tighten it all back up.

BenT
San Francisco