First of all welcome to the forum. I'm sure you'll find many questions about your new trailer and want to find answers to the ones you currently have and the ones that will pop up over time. Do some reading here and you'll find answers to most of them. If something comes up that you can't find or even that you don't know how to ask, just blurt it out and someone will probalby have an answer for you or at least be able to direct you in the right direction to get an answer.
As for your dealer replacing the wheels and tires, that's a good thing, but you might want to double check the brand of tires he put on your trailer. There are some "good quality" ST tires and there are some "not so good" ST tires. Do some looking on here by searching "tires" and you will find more information than you can read in one sitting.
As for quesitons to ask or things to look for on your PDI, go to this link
http://www.keystonerv.org/forums/showthread.php?t=5129
In the first comment, you will find a link to an excellent pre delivery inspection checklist. Print it out and take it with you. Use it as you go through the trailer and it will guide you through most of the issues you'll face.
Again, welcome to the forum, we're glad you're here.