Hey Ethan and welcome to the FISD! You're in good hands here.
No matter what armor you are going for, the first advise is research and more research. Read and follow other members build threads where you'll learn so much. The second advise is about the dremel. Practice. Find something cheap to cut up and just practice. Third advise, don't let all of the information here overwhelm you. We all have been where you are. When you get the nice big box of armor and start unpacking it, chances are you'll ask yourself what have you gotten yourself into. But once you start, you'll find its much easier and more fun than you thought! Take your time, measure and try on pieces a few times. Cut a little less than what you measure and try on the pieces again. If you're not sure about something, ask about it here....troopers helping troopers is what we're all about!
Take a look at the 501st web site and see where your local 501st chapter is and get signed up on their forum. Many garrisons have build parties where members get together and help each other.
Like I said, no matter the armor...research, practice, ask questions and most of all, have fun!
Good luck Ethan