I'll try to answer some of your questions, but I would highly recommend doing some more data mining in different threads on APC.
For lower time pilots, PS is looking for experience that expands your toolbox or directly relates to PS operations. For example, PC-12 time, turboprop time, corporate or charter experience, crew experience, etc. A CFI or II is also looked upon favorably. These differentials make less of a difference for higher time pilots.
PC-12 time is not a "dead end." It is also not a career accelerator. You will get more opportunities sooner if you fly something more "complicated" than a PC-12. However, the on-demand ops and IFR experience is a plus.
PS is a great intro to fractional and/or charter flight ops. We do all the same stuff as the big names, with the exception of fewer international ops and of course no ocean crossings. You'll learn a lot.
I've said it before; apply and find out. It's a good company and you'll probably have fun. YMMV.
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