After 9 years navigating the "wonderful" system that's our healthcare in this country (note the sarcasm....) here's my advice...
Read up on whatever you can about company's, deductibles, Out of pocket maximum, EOBs (explanation of benefits)---these are NOT BILLS.
Here's my example using our insurance. I'm 23 and covered under my dads insurance still (thank you ACA!)
Copays: this is what you pay every time you go to the doctor. For some insurance companies, there are also Copays for ER visits, radiology, lab work, etc. for us, we have a $20/$40 Copay. $20 for primary care and $40 for specialist
Deductibles: this is what you have to pay BEFORE your insurance will cover ANYTHING. And the range of dedcutibles is huge. Anywhere from a couple of hundred dollars to thousands of dollars. Also, there are usually individual and family deductibles. For example, we have a $500 individual deductible but a $1500 family deductible.
Out of pocket maximum: this is the MAXIMUM amount you will pay out of pocket before your insurance kicks in for 100% of the coverage. IMPORTANT: this usually DOES NOT include Copays and prescription drugs. That means that if you have a $5000 out of pocket maximum, even after you hit that, you would still have to pay Copays and the cost of prescription drugs
Coinsurance: this kicks in after you meet your deductible. For example, we have an 80/20 coinsurance. That means that after we hit our deductible, the insurance company pays 80% of the cost and we pick up 20% until we reach our out of pocket maximum which is when the insurance company picks up 100% of the coverage
EOBs- these are called explanation of benefits. These basically give you the breakdown of the services received and how much everything cost and what was actually charged to the insurance company. The insurance company is usually given something like 60 days to pay their share before they start coming after you for the rest ( or all otitis you either haven't met the deductible or if they deny it)
In-network: this means that a hospital or doctor is contracted with hat insurance company. This is what your coverage applies to most of the time. Some plans do have out of network coverage
Out of network- this means that the hospital, doctor or outpatient service is NOT contracted with that insurance company. This means that the insurance company will either not cover any of the cost or they will cover under reduced benefits ( explained in your package of benefits)
Also.....very very very important. Make sure you have coverage for ambulance transport and air ambulance transport. Not all insurance includes it and sometimes you have to purchase it separately. We are lucky because we have it included but it's not automatically processed and we got a $1500 bill from our fire department for a 3 block trip to the hospital whe. I went into anaphylaxis at my allergists office!!
Also familiarize yourself with pre approvals and the specifics of your insurance company. Each insurance company seems to have a different definition of "medically necessary" and I can guarantee that there are things that would be covered in Canada that probably wouldn't get covered here.
Also, check about what is being offered. Are you guys looking at a PPO or HMO? HMOs are more restrictive but should cost you less in the end ( unless you have to go out of network) and a PPO is more flexible but can be more expensive.
If you have any specific questions feel free to PM me. I have spent the last 9 years of mylife becoming an expert on navigating and understanding our broken system because you have to be your own advocate. Navigating our healthcare is not for the faint of heart ( no pun intended). And I want you to be better educated on the system than most US citizens are.
And i completely understand the major medical bills thing. We have "premium" health insurance and last year we racked up $22,000 in medical bills

we've racked up more than $100,000 over the past 9 years.