I've answered a couple here: will edit as I play about to find the answer to the others, so check back.
WNUMB: Sorry, forgot to add them. Wiki entry updated, but basically you split the four-byte value into 2 two-byte values, and they are used to find the address for the two banks.
STTIM (1): Yes, as far as I can tell. I opened up three windows in succession with a clock in it, each showed the same clock, with the time value from the previous one still ticking away in it. So the first one had 60 minutes, left it for ten seconds, then pressed [OK] when the clock read 59:50, and the second window had 59:50 in it which continued to tick down.
STTIM (2): Yes, it only has minutes and seconds, but if you do (for example) 1hr, 0mins, 0secs, the clock will read 60:00. So hours just translates into 60 minutes.
STTIM (3): The clock begins ticking down automatically as soon as you use a MESSAGE to open the window with the clock in it.