Hi Liming,
Although I don't control at a VATUSA facility that has PRM approaches, I have seen them used on the network and in real life. I'll do my best to provide some info.
1) Yes - at the airports where PRM approaches are published, they are routinely used when traffic warrants. I have flown PRM approaches at KATL regularly. I believe they are also common at KSFO.
2) I would imagine, like in real life, VATUSA facilities simulate the use of PRM approaches when traffic and weather conditions warrant. Specifically, I would imagine KATL to be a regular user of PRM approaches.
In real life, PRM approaches require special aircrew training and procedures. In practice, this is accomplished with simulator training plus additional briefing material pilots must go through prior to flying them. You'll hear if a PRM approach is in use with the ATIS, and with your approach assignment (normally given when you first contact the "Approach" controller). Flying a PRM approach is identical to a non-PRM approach, except for two things:
a) Once you've been switched to Tower, you must listen to a "monitor" frequency on a second radio. The controller may tell you to speed up, slow down, or can issue a "breakout".
b) If traffic on the closely-spaced runway doesn't fly its approach correctly, you may be given a "breakout" instruction: a turn and a climb or descent so that you can escape the risk caused by the other aircraft.
Hopefully one of the folks from a facility that uses PRM approaches on the network can provide a little more information on how they're simulated.
If you have any other questions, I'll do my best to answer them as well.