My question involves criminal law for the state of: Arizona.
Im 17 (7 months until Im 18)

Ill tell you the basics and then I have questions at the end for anyone who can help.

I havent seen another post about this crime in the state of Arizona, and I have read many posts about this, just wanted to get my own story out and get some questions answered.

About a week ago I was caught shoplifting from a Walmart in Phoenix. The total amount I stole was around $10. However, one of the two items i took from a larger package, which, in total, was priced at about $40. I was stopped at the doors by the LP and taken to a room. I was completely cooperative and respectful. He said the are going to press charges because the amount I stole was so high (putting it about $48, although the actual items in my pocket werent worth more than $10). I admitted to what I did, but I never signed any papers of any kind. The police came after a while, cuffed me, read me my rights, an questioned me. The LP and the PO asked a lot of the same things, and once again I was very respectful, admitted to what I did, and showed plenty of emotional hardship. I told them its the first time I ever stole anything from a store, and I dont know why I did it.

My parents had to come pick me up from the store. I was told that I would be receiving a court date and a restitution fee somewhere between $100-$250+the merchandise taken. Im not worried about this fee as I deserve it for what I did, and will pay it. Both the PO and the LP said this could never be removed from my record, but a lawyer my parents talked to said otherwise...

Here are some questions I have, a appreciate any efforts to help me or give me answers in this situation.

-Why am I being charged with $48 worth of stolen property when I stole less than $10? Can this be changed in/out of court? (If I person steals the gas cap off a lawn mower is he charged for stealing $500?)
-How long will it take to receive my papers for the crime? (I will be turning 18 relatively soon and I have told I need to get this out of the way before I can be charged as an adult.)
-Any ideas what a lawyer for a situation like this will cost? (My parents are rightfully making me pay for attorney fees and I need to know, approximately, what I will have to spend to get this behind me)
-I have read that I should plead not-guilty. Im sure my lawyer will help me with this decision but is it still worth it to do that when I admitted guilt over and over after being caught?
-They said I would be banned from that Walmart forever, can they really do this? (especially since I never signed any papers regarding this)
-This is my first offense of any kind, I am a straight A student and first in my highschool class with no background what-so-ever. Would you expect charges to be minimal based on my situation?

I appreciate any efforts to help me. I need a lot of questions answered so any response is appreciated.
Thanks guys.