This sounds like a recipe for their 60 Minute IPA?
I'll assume that's the beer you're talking about. I cloned this beer some time ago and it turned out pretty good. At DFH they 'continually hop' their beers, meaning, they add hops constantly throughout the boil (and they name the beers according to how long they keep this up: 60, 90, 120 Minute IPA's). So for my recipe, I added small amounts of hops every 5 minutes for the duration of the boil. Just be sure to mix your three hop varieties pretty evenly before putting them in muslin bags. The beer ended up with a beautifully crisp, piny hop character (mine was ended up ~60IBUs). I would recommend adding hops like this to anyone*. As written, I think the recipe should include more hops late in the boil, though.
The recipe I used only called for 6oz of Crystal malt. My version was decidedly dry; no real sweetness from the crystal that your recipe will certainly have. Admittedly, mine was imbalanced - but I like it that way. Decide how balanced you want your beer and perhaps find a middle ground?
As for adding half of your extract at different times, I wouldn't bother. People will tell say 'you get better hop utilization when your gravity is lower'. They're probably right, though I'm not sure if it makes a huge enough difference to worry about as small batch home brewers. If you add the LME at different times, you will have multiple hot breaks and potential for multiple boil-overs. Sounds like unnecessary hassle to me...
Hope that helps.
Good luck, merry Christmas! Let us know how it turns out
* If you decide to go this route, make sure you don't overdo the hop additions, especially early in the boil. Use a spreadsheet tool to make sure your IBU's end up where it should.