Moving from Non-Resident Alien to Resident Alien status: nuances

[Fedor]

Hello everyone,

I have a series of questions related to filing taxes as a Resident Alien.

1. I am an international student, have been in the US in F-1 status since 2018. For all these years I was filing my taxes as Non-Resident Alien. It turns out that in 2023 my status has changed and I became a Resident Alien for tax purposes, so now it is the first time I need to file my taxes (for 2023) as a Resident Alien. Am I correct?
2. I have a wife who has been in the US for almost the same period as I am in F2 status. If I understand correctly, she transitioned to the Resident Alien status in 2023 as well. Am I correct?
3. My wife has no income both in the US and abroad (as required by the dependent immigration status). Consequently, she doesn't possess an SSN, and we haven't applied for an ITIN. As a NRA I always filed my taxes as married filing separately and she filed only a 8843 form. The question is how we should file our taxes now as both being Resident Aliens. Based on what I have read, it looks like we have two options - report taxes as married filing jointly or as married filing separately. The first one, however, requires my wife having ITIN so we can first apply for it (which is not a good option as the filing deadline approaches). Some people recommend us to apply for extension and file taxes later when she receives ITIN. Is this a viable option, with no adverse consequences?
4. Another option is to file as married filing separately. If we decide to go this way what forms should my wife provide if she has no income, no SSN, no ITIN? As I mentioned, earlier she filed only a 8843 form but it looks like it works only for NRAs. I would appreciate any clarification on that point.
5. We live in Colorado state. Before this year I filed only a state form for me. How does it work for Resident Aliens?
6. (probably the stupid one) We have a 3-year-old son who was born in the US and is an American citizen. Should we file any form for him? When we both were NRAs, we filed nothing. Are things different for Resident Aliens?

Thank you!