Yeti Clone- Mash Tun size and Mash Temp

[jasonclick]

I'm planning on making a yeti clone scaled up to 10 gallons... i've never done a 10 gallon brew or brewed a stout.

Here's a link to the recipe:
http://beersmithrecipes.com/viewrecipe/12542/yeti-clone-ver-20

I've got 2 questions:

1. since this will be roughly 40 pounds or grain, will it fit into my Sanke Keg mash tun?
2. If you look at the recipe, it says to mash @ 149 F for 90 minutes. Wouldn't that be a thinner beer? I would think I'd mash around 156 or so. I'm sure I'm missing something there

Thanks for the help!