ACA / CHIP questions

Looking for help navigating ACA and CHIP

I’ll be retiring early and am not old enough for medicare. My income for 2022 will be high, but for 2023 I expect to be at around 300% FPL to qualify for subsidies.

Couple questions on ACA – didnt see the answers to these in the Healthcare101 post

– Is there any advantage / disadvantage to having the subsidies directly applied to your premiums vs paying full premium for the year and taking the tax credit? I’d think you’d want to have the subsidies directly applied to minimize costs now.

– What if have the subsidies directly applied to the premium but end up grossly miscalculating my estimated income and I end up not qualifying for the subsidy at the end of the year. Is the difference owed calculated when I do my taxes the next year? Is there a penalty?

– At 300% FPL, the marketplace is only offering me plans for myself and my spouse, and saying that my son (under 18) should use CHIP. Is the quality of care from a CHIP plan different than that on the marketplace? Can the marketplace price out a plan for the 3 of us as well (if i increase my income to get the premium for spouse+child the subsidies go away).

– Do the ACA plans provide coverage nationwide? So if something happens to me while travelling in another state will i be covered?