You can install the air intake easily yourself, with basic hand tools. Your intake system is essentially four parts on the right side of your engine right now: A black scoop-looking thing that connects to your bumper, a black box with an air filter in it, a black tube that connects it to the engine, and a smaller black tube that has a chip on it, connected to a wire. That is your mass airflow sensor (MAF). Essentially, what you want to do is unbolt ALL of this, with a basic screwdriver and socket wrench. Once it's all off, your intake should come with several things: Piping, couplers, clamps and a cone-like filter. You're pretty much going to connect the pipe to the throttle body, where the old pipe came off, then your MAF, then the filter.
This is what your intake looks like now:
http://imageshack.us/photo/my-images/820/082310114400.jpg/sr=1
This is what it should look like when it's done:
http://www.roadraceengineering.com/3g/parts/aem/3gaem-cai-barry-02.jpg
As for the vacuum, he probably means there's a vacuum source somewhere in the intake system. If you see in the first picture, there's a vacuum hose that connects from the top of your engine to the intake pipe. It should have a place to hook up to on your new intake; that should seal that vacuum leak.
If you need any guides on working on your car, check on club3g.com.