Do the instructions describe how to calculate with the slide rule bezel?

Well, sorry about the instructions, but slide rules are not that difficult. The slide rule uses two identical logarithmic scales. It operates on the principle rule that log(a) + log(b) = log(ab) ---which means that you can do multiplication once you have two identical log scales next to each other. To multiply, just line up the beginning of Scale 1 (usually starts at one or ten) with the first number you'd like to multiply on Scale 2, then go to the second number you'd like to multiply on Scale 2 and read the answer on the opposite side. All you've done is add two logarithmic amounts of something and used a fancy property of logarithms to read what number the multiplication would be. Division is just the first minus the second, so you line up the big number to divide with the small number, then go in reverse to the 1 (or 10) to read the answer. Unit conversions are just multiplication or division problems, and have their own markings for where you'd multiply by. Dunno if that helps. Good luck.

Does the large second hand move?

The large hand does not track running seconds- that duty is appointed to the bottom subdial of the watch. The large second hand engages only when you start the chronograph (stopwatch function) of the watch. The other subdials track hours and minutes for the chronograph, giving it a 12 hour total possible runtime.

Is it good for large wirst size?

I'm a big guy and needed to take two links out of the band to wear it. It's still looser than I would like. I really like the watch it's my daily daily time piece.