That's incorrect -- it's not minimum to maximum. It's 4500, variable
to 500. In the ops specs for every airline operation with which I'm
familiar, including my current 121 airline, the "variable" portion is
advisory only. So as far as weather for starting the approach, it was
4500.

Hmmm, I was going by the various METAR decoders I have and a look at the
FAA's Aviation Weather Services publication (AC 00-45E). A detailed
breakdown at the following link:
http://www.met.tamu.edu/class/METAR/metar-pg8-RVR.html

This is academic parsing, and may not reflect actual practice.

I don't have much info beyond that, specific to SWA. The HUD is an
option on the next-generation 737s, and many of SWA's are so-equipped.
It's a real safety enhancement in low visibility. (That should also
discredit the notion that the airline skimps on safety equipment -- it
doesn't.)
Here's a picture of it in one of their cockpits:
http://www.airliners.net/open.file/868375/L/

Very cool, thanks. Since it only exists on the captain's side, I wonder
what the CRM procedure is to shift roles if the first officer is the Pilot
Flying.

Thanks for the link.