Rod, in my case, I didn't apply for Medicare, THEY APPLIED ME! They sent me junk that said I can respond or not respond. If I didn't respond, they'd sign me up anyway. Either way, no choice for me. It was just there.
Basic is only for hospital. You need more? Supplements: B,C,D. I just chose B for now cuz I ain't on any meds and never have been. Oh, I know, the day will come.
You WILL get bombarded with offers from supplemental carriers. Trust me, you won't have to do the research. They will contact you and all you hafta is decipher what is BS and what is not, what you want and what you don't want.
The plan B supplement is around $100 a mo. You want more, of course the cost goes up. Around $100 more for each plan. You can add or subtract what you want but you WILL be forced into Plan A. That's all I know for now cuz that's all my experience with it. It's only been 5 mos for me.