ZippyNH

Welcome!! Just a line pilot here, not a trainer or management Pilot. Have about 2 years at AMF, but closer to 9k hours, about half of it in cargo.
Training is the typical "drinking from a fire hose" and a bit old school. Honestly when you are alone, you must perform...sometimes some people can be shocked that it's not "spoon fed" at times, but hard work and a reasonable attitude it goes a long way.
Ameriflight's version of 135 is a bit closer to 121 than most...we get a full release from dispatch, get flight plans filed, etc...we still must do performance, W/B, limits, etc...so the transition shouldn't be too terrible.
Under 135 we are often much less well supported on the road...yes we have a phone and lots of people to talk too, but must be able to think on out feet, talk to FBO's about gpu's, even plan for hangers if snow is expected in some locations.... We exercise judgement regularly and unlike some jobs can't operate through a simple yes/no flowchart.
It's much more than just moving metal, it's truely paying attention to EVERYTHING going on to get the job done.
For Training, an active pilot should most pay attention to old school stick and rudder hand flying skills on a 6 pack.... equipment varies from plane to plane even with a given model, some lack even a GPS, so be ready to tune VOR's, use dme's and RMI's, with generous amounts of hand flying.
Personalities tend to make cargo pretty rewarding IMHO, the job and lifestyle fits some personalities better than others.....some people enjoy it and have a blast....for some the grass will always be greener on the other side of the fence.
​​​​​As for stability, it's as stable as the customers let it be, lol.
some bases have been closed, one moved, and another just opened so it's largely luck of the draw as to the long term prospects at any base. As the largest 135 cargo operator there are certain advantage's compared to many if the one/two base or regional operators...the extra stability is nice, but so is the jumpseat privileges that are somewhat rare under 135, along with the possibility of going from a turboprop to a 767/md-11/a-300 for those who desire it...who knows if those programs survive, but personally know people that have both gone to 767's for GOOD/GREAT companies in the last year.
Know this response isn't direct point on point, but hopefully it will shed some light on things. No place is perfect, but some people tend to work better with others and find a way to get the job done and others always look at things and somehow feel they are getting the shaft.
Many issues that people have have been due to the fact the AMF has been seriously understaffed for a couple years, and some pilots are angry that the smallest plane in the fleet, the be-99 was left out of the most recent bounus plan.... EVERY company had BS, it's just a different flavor and color!!
Good luck, hopefully you get the call and I will run into you on the road!
And you know the old saying?
You truely aren't Pilot till you have been through at least one bankruptcy, shutdown or furlough!! Many of us have been through it too.