Illinois ACA Pan, child attends college in Ohio

I’m very likely losing my job soon so I’m trying to get ready by doing all my ILLINOIS ACA research now. Regardless of when I get laid off, I understand that is a qualifying event and can get an ACA plan at that time. I have researched like crazy, but have a few questions I’m not certain of:

I have a child attending college in OHIO. Can I add them to the family plan (myself, spouse and high school age child), or do I have to get them an OHIO plan? That doesn’t feel right their permanent address is ILLINOIS, but they spend a lot of time in OHIO (obviously).

Whenever I do end up joining the ILLINOIS ACA, I won’t have income. How do I calculate income in order to price all the different plans? I *think* that if I set the income too low it will move my one child to Medicaid, set it too high and I don’t maximize the discount.

I’m sure the answers will create more questions, but know what to do with these two will be very helpful. I can’t believe I’m not smart enough to figure all this out on my own… I’m most grateful for any advice.

PS – I capitalized my state above as it seems that different states have very different approaches, and I wanted it to be clear where I am, and where my one child attends college. (I wasn’t yelling! :-))

Thank you Reddit Community!