Hey 1stTimer, one piece of advice I will give you is to locate the stainless steel fender washers first. That piece is not standard stock at your Home Depot/Lowes type stores. I had to go to Fastenal to pick mine up. It wasn't a big deal once I found teh store as they had them in stock and they're cheap. However, it set me back a week because I went to Home Depot to get all my supplies the night before I wanted to brew and they had everything I needed to make the mash tun except for the stainless fender washers.
Another piece of advice: Go with the 10 gallon cooler if you have the space.