If you have meds like amphetamine salts that are schedule II, I do not think Customs will let you keep them. I also would bring with you your prescriptions. I would call US Customs and Border Protection to see if they will allow you to bring your meds into the country. This needs to be done. Do not assume this part will go well for you. Be proactive.

We do not have universal health care. You need to purchase your own health insurance, or work for someone who will provide this to you. If you qualify as having low enough income, the government can subsidize this for you. However, many do not have health insurance because they simply cannot afford it. You would not qualify for disability, but may partially qualify for Medicare. You have no employment history for SSDI. For instance, SSDI turned me down the first time because I was missing work history for an important time span. I hear there are some kinds of public benefits that are available from both the state and federal government to green card holders.

I do not think it would be appropriate to immediately go on Medicaid as soon as you get here. For one thing, I suspect you need to become a resident of a state before the state is willing to place you on their welfare system and provide you with money. Residency requirements depends on ones particular situation, but can be as long as a year. Furthermore, some states require you to be a resident for five years before you can be elgible for their Medicaid. So it will pay for you to research this thoroughly before coming here.

I would first establish an address. Then I would find a pdoc which you can do online. Use this address when filling out paperwork as a new patient. I also would get a cell phone. Once again, you need an address for this. There is not much you can do here without some sort of home address and cell phone. I would open up a bank account. During all of this, I would be searching for a job, any job to start out until you figure things out. I hope you are bringing enough money with you to set yourself up for at least several months.