What can I expect to be doing as a 35F assigned to an ARNG artillery unit?

Talk to your first line S2. Ask about Foundry training courses. Stay on top of your profession.

I'll re-ask the same question as Major Landgren (see below)...what's a 35F ? I was an active duty tank unit commander during the Cold War/Viet Nam (then 1203), and became the Assistant S2 of our local Mechanized Artillery Brigade in the active reserves following my regular, full active-duty commitment. I have absolutely no recollection what my MOS in that position was. Heck, it was in the '70s. Can't wait to see other responses to your inquiry !

Spent 4 years in the AL-ARNG as a 35F before switching to Active Duty and Commissioning. Though I was in a CSSB, your experience might be similar to mine. Lots of vehicle PMCS and 350-1 training. You probably won’t do any significant amount of MOS relevant training until an AT, and even then it’s hit or miss. Ultimately, it will largely be up to you to seek out opportunities and to learn. Get a feel for your unit first, but seek out additional MOS relevant schools where available. I was able to get two deployments and stayed on consistent ADOS orders while in. It will be easy for you to stand out. Excel at PT, Shoot well, show up on time, and be dependable. You’ll already likely be well ahead of your junior enlisted guard counterparts. Make the most out of it. Max out the benefits and get your degree. The Guard will be what you make of it. Stay motivated.