Ok, so it is my first all grain brew, give me a break.
I was having some leakage on the mash tun, so I stuck a small pipe wrench on there to tug on the ball valve a bit to make a better seal, which you can see in the picture. It did the trick well enough. I ordered some of those 5/8" ID washers over a week ago to perform that function, but they haven't come in yet.
Mashing went ok, for my first time, I suppose. Having never used this mash tun before, it took several tries to stabilize the temperature and it dipped below 150 a couple times. I had to add 3 quarts of hot water to get the temperature up. Less than ideal, but oh well. I already know how I can do better next time. I did the iodine trick and it seemed ok after about 75 minutes.
After that, lautering went fine. I used the stainless supply hose and no stuck sparges or anything like that, though it did slow down substantially towards the end. The refractometer gave me 1.08 SG out of the MLT right as I was hitting 6.25 gallons, so I guess everything worked out.
I am currently boiling with about 30 min to go. I was a bit worried about boiling 6.25 gal in a 32 qt kettle, but the hot break wasn't so bad, at least with this recipe (brown ale).
Thanks to everyone on this site for getting me to this point.