United Health Care Medicare Complete Did I make a mistake on joining this plan? Internet

Greetings to all concerned Americans. This report is about Medicare in general and maybe the lack of understanding. No specific complaint at this point, just expressing my feelings and hopes I may get some feedback on my experiences since I turned 65 in June of 2012 and if others are as confused as I am.
 
As I approached the age of 65, I started receiving numerous mail from Medicare stating I should be aware that I would be soon be  "going on" Medicare. Before I was even able to check things out, I received my Medicare A & B card in the mail, stating $99 would be deducted from my Social Security check, I believe it was in May. I talked to many folks and many said, "you will need additional "gap" insurance to cover the 20% Medicare does not cover." Perhaps I should preface this with the fact that I have had VA Benefits since 2003. Still many said, "If I need to go to an emergency room and I am not close to a VA facility, and am admitted to a hospital, I will be responsible for the 20% that Medicare does not cover. This could mean thousands of dollars I am responsible for. In talking to many people, they said they are paying anywhere from $140 and up for this "gap" insurance and it would be taken directly out of my Social Security account.

I then started seeing commercials on TV for residents of Clark County, NV. that would qualify for a plan thru United Health Care, that has no monthly premium. Only pay for what you use, called Medicare Complete HMO. You need to stay within their network of providers. Since Jan. 1, 2013 I am finding it difficult to find a "Primary Care Physician" close to me and waiting periods of 3-4 months to have an appointment. Is it true, when you sign up for this program, UHC takes over your Medicare and the now $104.00 per month for the original Medicare A & B gets paid to them?

I now need to find out what position I have with my VA benefits. I want to continue as was with VA and use this UHC Medicare Complete policy only as needed and I understand I am locked into the UHC for at least a year. If and when I find a Primary Care Physician in the network, can I change PCP's as I desire. Much was not explained by the Rep that signed me up for this policy.

Any comments from readers on if they are using this type policy and their experiences?