Questions on Native American zero copay benefit on ACA Marketplace plans

My family is Native American, below 300% FPL and qualify for the zero cost sharing benefit on ACA marketplace plans. I’m currently in the process of signing up for a marketplace plan and have a few questions that no one seems to be able to answer:

I’m self-employed and slightly below the 300% FPL income limit. There’s a small chance in any given year that I may unexpectedly have an unusually good year and go over the 300% FPL. If this happens, will I need to pay the insurance company back for the care we received earlier in the year with zero deductible, copay, etc.? How does that work?

Is out of network care still paid with zero deductible, copay, etc? If so, would it be in our best interest to enroll in the absolute cheapest marketplace plan that has no in-network providers in our area? Since out of network care should still be fully paid with zero cost sharing? Any catches I’m not realizing here?

If we enroll in an HSA eligible plan but then get the Native American zero cost sharing benefit, can we still make tax deductible HSA contributions? Or does the deductible changing to zero make it no longer a high deductible health plan and therefore ineligible for HSA contributions?

Thanks for any help or advice anyone can provide!