Thoughts on my 1st partial mash recipe, an IPA

This recipe was composed using beer smith, and is intended to resemble SNPA 2009 Anniversary Ale. I say resemble because they're using Chinook for bittering and I plan on using Magnum, since I just ordered a pound (along with Cascade and US Saaz) from Hops Direct. Based on guidance from the "if you could only choose 3 hops" thread, I'm going on the assumption that as long as you reach the proper IBUs (which, the type of bittering hops does not matter that much. My scale is only accurate to tenths of ounces, so I did not try to get too crazy with hop measurements and instead relied more on timing to get the IBUs dialed in (which is why the magnum is boiled for 39 minutes).

Speaking of boil times, if I am sacrificing more hops in favor of shorter hop boil times, can I reduce the overall boil time from 60 minutes to the longest hop boil time (to save on time and evaporation) or does the wort need at least 60 minutes regardless (think I read this somewhere around here as well).

This will be a partial mash, likely using a 3-gallon cooler rig (yet to be built) and a 10 gallon brew pot, which will allow me to do a full boil (boil size was determined based on my last batch using this pot and the amount of top-up water I had to add). Please share your thoughts.

Style: American IPA
TYPE: Partial Mash

Recipe Specifications
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Batch Size: 5.00 gal
Boil Size: 6.12 gal
Estimated OG: 1.061 SG
Estimated Color: 9.0 SRM
Estimated IBU: 46.3 IBU
Brewhouse Efficiency: 75.00 %
Boil Time: 60 Minutes

Ingredients:
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4 lbs 9.6 oz Extra Light Dry Extract (3.0 SRM)
3 lbs 8.0 oz Munich Malt - 10L (10.0 SRM)
8.0 oz Caramel/Crystal Malt - 40L (40.0 SRM)
0.80 oz Magnum [14.00 %] (39 min)
1.50 oz Cascade [5.50 %] (15 min)
1.50 oz Cascade [5.50 %] (Dry Hop 7 days)
1 Pkgs SafeAle US-05 (Fermentis #US-05)

Two points:

1. You can reduce the boiling time, but you'll have to reduce the boil size a bit.
2. Dry hopping is not s substitute for an aroma add. I did that a couple times early on and was very disappointed in the results.

Thanks David... Since I'm rather new to this - this will be my 5th brew - I'm still al little fuzzy on where the line is between bittering and aroma in relation to timing. Is the 15 minute 1.5 oz Cascade boil not a sufficient aroma add. Should I add an addition at the end of the boil, right after I kill the heat? If so, how much? And, with this addition, do I need to change the amount of the other hop additions?

I'll do some calculations on how much less water to use if I reduce the overall boil time.

Also, the more I research into partial versus full mash, I'm leaning towards just building a full mash rig (using my 26 qt fryer as an HLT, 5 or 10 gal igloo/rubbermaid MLT and my existing 10 gallon brewpot - probably the 10 gal MLT since there's a tripel in my future) since it won't cost much more than the partial mash rig and the cost will be recouped in grain versus extract savings ion 2-3 brews. All grain plus bulk hop purchases saves a lot of money in the long run.

Thoughts on a new hop schedule?