It won't hurt the vanagon pump, at least it hasn't hurt mine, but you
may have to crank for seconds, or repeatedly over a few minutes to get
it started due to air in the lines.  I did have a Saab once with a
submerged pump in the tank, and if you ran that dry for more than a few
seconds you would destroy the impeller, which was lubricated by the gas,
and the pump was $250.

The problem of picking up crud is usually due to water contamination in
your gas.  It will stay on the bottom and not cause problems until it
gets deep enough to be sucked up, this is why some gas is always left in
the tank, it might actually be water!  Depending on the humidity and the
frequency of reaching the dew point, leaving the tank partially filled
continually can lead to condensation on the tank walls, so it is best to
fill the tank all the way each time you get gas.  (I used to have a
friend in college who never had more than $2 in his pocket at any given
time, as was the case with most of us, and he ran his car with the fuel
warning light on all the time, never putting more than a dollar's worth
in the tank (two gallons back then!), and sure enough, water condensing
in the tank did that car in in two wet winters here.)

The level of fuel has nothing to do with the level of water.  Usually
water in the gas is not a problem as long as you frequent major brand
gas stations and your gas cap seals properly.  Now that gas in major
metro areas has ethanol in it in the winter, any water in station tanks
has to be removed completely, so problems are rare.

--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Driven since 1969)
'74 MGB GT (Restoring)

Assisting on Restoration:
'72 MGB GT (Daughter's)
'64 MGB (Son's)

Parts cars:
'68 & '73 MGB, '67 MGB GT