Plants do not need aeration. What fishes love, plants hate. And vice versa.
Mulm is the black stuff that comes out of your filter when you squeeze the sponges or after you drain the water in your cannistor filter; it collects at the bottom. It contains lots of bacteria.
Peat is a usually dried spaghum moss, you can find this product at hardware or gardening stores. Sprinkle a small layer below your substrate when setting it up. The bacteria in your mulm will feed on the dead organic material in peat and thus proliferate faster and help your tank cycle quicker, along with helping your plants as well.
I suggest you read up http://www.rexgrigg.com
before starting out your planted tank. You'll find that the world of planted tanks is a totally different one from fish-only, and some good reading will make it easier for you to get your tank up sucessfully