That seems to be about 1.3 quarts of water per pound of grain, so that seems about right for the mash.
The thing with a big grainbill, you tend to lose some efficiency because of having less sparge water to get to your boil volume, but in my case my efficiency is always better when doing decoctions so it evens out when figuring out the probable OG.
I never do a mash out when I batch sparge- there really isn't any reason to as the first round of batch sparging can be a bit hotter and works as a mash out.
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