Help-trouble submitting coins.

To start off saying I'm new to coin collecting would be a serious understatement. I just started collecting a couple months ago when I was on a business trip to the Maryland area and I caught a show on the television, since then it's been all about coins. So I've been trying to complete some fairly easy sets to start out with, like the Sac's and Presidents, and I say easy because right now they are in my price range. But this leads me to my questions on submitting coins. I have never done this and I am trying to get the hang of it so if these are dump questions I do apologize, I just want to make sure I'm getting it right. I'm trying to submit some of my 2009 Proof set coins and I'm thinking they would fall under the modern tier, is this correct? Also why do some coins I see have just BU on them? I would like my coins to come back with the actual grade on them like PF70UC so on and such forth. Like I said thanks for taking the time to read this any help would be greatly appreciated. I've learned alot so far from this community and all it's members. Thanks again. Jeremy