>1. Is anyone aware of the type of 717's they operate?
They are all -2BL models, ex Midwest Express, leased from Boeing Capital. Most were delivered by Southern Cross ferry pilots.
I don't know about the HGW option; the 717's certification TCDS was updated so that it only lists the HGW MTOW (54,885 kg ) without a break-out of individual frames, so you'd need someone familiar with the actual airframes to check the docs.
Ther are two engine options, the A1 and C1, but I understand that it's just a software tweak to gain the higher thrust.