This is really a modem-related question:
1) Every so often (it's getting more often, it seems... < 1 hour) my modem
stops sending data, then a 1-2s pause, then CLICK... hangs up.

I am guessing this is either a line quality issue (my modem says signal
strength is -30dB) which I have no control over, or a cabling issue
(have yet to check that - it's a Radio Shack cable) or a UART problem.

Assuming it's a UART problem, I have a "DSP" Dual Serial, one Parallel
board that uses a "Startech ST16C552CJ" ASIC, or so it would seem.
NetBSD calls it a 16550 on bootup.  Is it sufficient to hold a 14.4 line
or is it an unreliable, cheap clone that is the root of all evil?

It's getting really aggravating.