For one, 7 lbs of LME is a wee overboard (not necessary, but you can use it).
Depending on the hops AA%, I would use all the hops at 60 mins (boil). HWs generally use only bittering hops. You probably told Promash the AA% so its guess is better than mine at the moment. Most of my HWs are about 7-8%AA and on the sweet side, not bitter, but then again I only use 5.5-6 lbs of DME.
The grain isn't going to add more body, but Malto Dextrin will, but I'd say it's not necessary. HWs are generally sweet, lighter, and more delicate with a medium body. I think your brew will achieve that without adding anything.
But...then again, it's all about personal preference.
