My ds is almost 23 months old.
Vickie, Hi and welcome to the Toilet Teaching board.
You DS is starting to show the signs, and I would just go with it for now. You may want to check with your local library and see if they have potty training dvd's/books for kids, an allow your DS to start watching the dvd's and read the books. Then you have off he will be very familiar with what he should do.
Training pants are think cotton underwear it can be found in many stores, and online. It is not required but can come in handy if you will away from home, if not just the vinyl pants to go over the underwear are helpful. If you are going to be using a rewards chart you woul need the chart, and the rewards you plan on giving. I hope that helps. Please keep us updated on your DS progress.