What kind of field training should a 42A expect?

It surely depends on what unit you are placed in. I was previously in a strategic unit and all we did was have someone in the S1 shop 24/7 for 2 weeks the duration of our FTX and all we wear is our PTs off duty and ACUs on duty. Then I PCS'd to my next unit and we went to JRTC which was a month but half of it was the actual FTX, No Showers and No Phones, just training and suck.
In my experience whatever unit you're stuck with, you do what they do.

I hope by this time, you fully understand the PPW, ERB, SRB, and EMILPO, and at least a good bit of MyPay.

It would help if you declared your unit and duty station. That said, as a 42A your place is behind a desk 99% of the time. Our 42As in the 101st ABN at Fort Campbell got some FTX time, but it was exceptionally rare and they weren't conducting battle drills. As far as humping a ruck that depends on your platoon PT plan. Don't be surprised if it's a regular event.