When you have long sits in cities, are you required to be at the FBO/HOTEL etc or can you hit the local course/sightsee etc?

This depends on the type of stby, there are a few different ones. Hot Spare: plane is fueled and ready to go within 30mins. Airport standby: Little less ready than Hot Spare, 45mins to an hour to be ready. Hotel Standby: usually given when the plane is broke or if there is nothing going on, they would like you to be able to leave the hotel within 30-45minutes but as you get to know the company you will be able to easily tell how far from the hotel is safe. Then there is rest and minimum rest at NJA is 10hours and occasionally you will get a lot more. I have had 18 in MYNN so we got to do some exploring, just depends on your fleet. During rest you are free to do as you please and they cannot interrupt it once assigned (12hr rule for alcohol applies).

I got another question. Sorry for all the Q's you guys are really good. Say you are based in MHT. Have far would they use ground transportation for you? Say for example we have a lot of airports within a an hour or so from MHT like BED, BOS, BVY, OWD, even CON, PSM, or PWM.

Short answer: as far as they need. They can assign a rental car for trips no longer than 150 miles or 4 hours. Unless you volunteer for longer, they'll get a taxi, a sedan with driver, or something like that. (If there's a safety issue with a rental car trip, like you not knowing your way through downtown LA, or you're dog tired, you can refuse the rental car.)

From MHT, I can certainly see getting a rental car or driven sedan to any of the Boston-area airports. PWM is under 100 miles, so that's certainly a rental car possibility as well. It's all done during your duty hours, and at company expense (including the fuel for the car). You'll likely take an airline flight out most of the time, though.

Per diem pay
 

What are the rules governing per diem? Are they paid 24 hours a day or just for when on duty. When do they start and finish? Thanks.

It starts at your show time on day 1 and ends at off time on last day.