Thank you for this post! My parents and I flew out of it on my way to JFK
last summer. Basically, if you have a certain American Eagle flight you are directed to a "gate" in the B concourse when you check in (I forget which one we used) and from there you see a sign that says "SHUTTLE" or something that like. It directs you down a flight of stairs and you walk onto an awaiting bus on the tarmac. From there you are driven to behind where the cargo (FedEx etc...) planes park and there is a small terminal there. There are no jetways, but bridges of sorts to load you into the awaiting planes.
The inside of the terminal is kinda cramped, but there is a Hudson News and I think one other store (not sure). It's in OK
shape, but it's really a hassle to use if you want my opinion. I don't look forward to ever flying out of that terminal again. There are great views of the ramp though.