Trying to understand US health insurance

Sorry if this isn’t allowed.

I’m Canadian and just curious and just for the record not here to criticize it in any way as our system is far from perfect.

So this is my understanding so far. You get a policy , you pay for anything medical related up to your deductible. After that your coinsurance kicks in to your policy max and then everything is 100%covered. Is it true you get one free routine exam?

The part that confuses me. Let’s say I was to sign up for a policy tomorrow . I have to find a family doctor that is the “network”. If they refer me to a specialist is has to be in this network. If I go to a hospital it has to be in the network? Even if it’s an emergency it has to in the network. The network thing is what I’m most confused on. And you have to get permission from your insurance company to get something paid for?

Also does your insurance ask you if you drink, smoke, drugs? Does that affect your premiums? And for making claims does that affect your premiums , like a car insurance policy.

Thanks for reading.