Redex
Flying the Pc-12 is not hard, especially being a turboprop since there is no mixture or prop to control. The lack of SE time won't be an issue, what will be the issue is that you must have either a Commercial SEL or a SEL ATP.

The majority of the fleet is the NG but all the new 12s are NGX. Both aircraft have the Honeywell APEX.

You can upgrade whenever you want or stay as an FO if that is what you want. However you can't go part-time until you have 100 hours as a Captain.

As far as the island flying that is done by all the bases. However since you are over 65 the only international flying that you will be doing will be to Canada. That is not Planes Sense's decision but an ICAO rule which happened a couple of years ago. The rule says no commercial flying if over 65 unless a county specifically allows it. The US and Canada does while the Bahamas, Mexico, and other Caribbean countries don't.

I'm in my 70s, and not the oldest pilot there, and us old timers are treated fine. In fact we are treated as if we are just one of the guys, which we are, so age is not an issue.