"CompleteNewb" wrote in message
1) with a cutoff valve being right above where this leak is, can I assume
that shutting it off and draining the water heater a little bit will give
me a water-free inside of the pipe at that point so I can successfully
heat up the pipe enough for solder?

May work as long as you can get some air into the tank to displace the
water.

2) Assuming "yes" to the above, will solder flow upwards into this joint,
"sucked" up by the heat?

Yes
Clean the joint as best you can. Wipe some flux on it. Put the heat right
on the joint where the leak is until it get hot enough to melt solder when
you touch it to the joint. Put a quick wipe of solder, then wipe the joint
with a rag.

You want the point of the flame above the joint where the tubing slips into
the valve, you want to touch the solder right on the joint. The entire
procedure will take but a minute or so.
--
Ed
http://pages.cthome.net/edhome/