Thai universal healthcare

Recently got my Thai citizenship. I live overseas but plan to spend some extended time in Thailand moving forward. Have some questions about the universal healthcare scheme that I can’t find through regular googling (maybe it’s just in Thai and not translated to English?!)

1. How would one start participating in universal healthcare? Is it automatic once you’re a citizen? Or do you have to apply?

2. Is it just attached to my Thai ID card? (Ie. If I have an infection, I can just go into a hospital, show my ID card and pay 30 baht to see a doctor?)

3. Can I access the healthcare if I’m only in Thailand 3 months out of the year?

4. What exactly is covered under this scheme? Like, is chemotherapy covered?! Or annual physicals? Or is it really just colds, flus and Covid?

If anyone can answer or direct me to a website, I would be thankful! All I can find are scientific studies and Wikipedia if I google it :/