1) Don't know. Sorry. Have you checked their web site? This isn't a blow-off. Last time I checked, their web site had charts with entries like barrel length, type of finish, type of sights, etc., for the various models. It seemed like a convenient way to compare them at a glance.
2) My early P85 has the manual safety. It starts out like a decocker - when you rotate it down, the hammer falls (without firing, one would hope). The hammer actually does fall at full speed; it doesn't lower slowly. Unlike a decocker, it stays in the down (safe) position - it doesn't return to the upper (fire) position under spring power. While down, it acts like a safety - it disconnects the trigger. You have to manually push it back up to the fire position to fire the gun. The first shot is double action, followed by single action, in the usual fashion.
Personally, I think it's not only unneccesary, but it's really a liability. I was taught to use it like a decocker, that is, to immediately push it back to the fire position after dropping the hammer. I forgot to do this once - once. I came out of the holster and got a dead trigger. It took me a couple of seconds to figure out what was wrong. Luckily, I was on the range at the time, where it was only embarassing.
The short version: go with the decocker.
