You can do "outside flying" but you have to get approval from the chief pilot. But you won't be approved to fly the Pilatus, as that would present a conflict of interest. A lot of guys do stuff on the side, from what I understand. One of our instructors picked up a ton of extra days last year and he got 700. I would think you could expect ~ 450 per year. They fly in real weather, icing conditions, low via takeoffs. It is impossible to reliably predict IMC time. Like you said, upgrade is based on merit and your previous experience when you get here. You can expect to be ready to upgrade within about a year. You will need 1500 hours. They look at how well you do your job as an FO.