Aloha Dyln and Welcome! :wavey:
You've asked two questions, and to answer them ... .
First, the best way to figure out how this site works is just to spend time on it. Check out the various boards and even the chat room and see what's there. If you have any questions, don't hesitate to ask; we're a friendly group and I'm sure that someone (or several someones) will be more than happy to answer your questions for you.
Second, your question about the 'AP' pins. One of the things about pin trading is that the value of *any* pin is in the eye of the beholder and, at the end of the day, a pin only is worth what someone is willing to cough up, be it in other pins for trade or $$$ to buy, to acquire it. While most people generally agree that some pins are 'more' valuable and others are 'less' valuable, the 'exact' value might be up for negotiation. After all, the most valuable pin in the world could be valuless to you if you absolutely detest it (because you wouldn't pay a penny for it, right?).
Which brings me back to AP (Artist Proof) pins. These fall into a very subjective category. Some people value them highly and, as such, are willing to trade higher or pay more for them because of that 'AP' on the backstamp. Some people don't really care one way or another, simply because, for the most part, the only way to know a pin is an AP is to check the back for the 'AP' backstamp, and as such, don't value them differently or much higher than the released version. Some people don't have much interest in an AP version of a pin unless it's *visibly* different than the version of the pin that was released (that is, they can look at the pin and know it's an AP without checking the back).
I hope this helps.
I am still trying to figure out how this site works and all that it offers! 
