Making root beer is easy, but I'd recommend plastic (not glass) bottles.
I always used 16 oz coke bottles, and that worked perfectly. If you use plastic bottles, you can stick them in the fridge when they feel hard and not have any bottles blowing up.
One the easiest and best tasting root beers I've done (with bottle carbonating) is the cheapest as well. I used McKormick's root beer flavoring from the grocery store, and followed the directions exactly. Champagne yeast is great for soda, and you only need a tiny bit so you can reclose the package and use the rest later. It turned out really good!