2-row pale malt needs to be mashed (mini/partial or all grain)
crystal doesn't need to be mashed (steeping) but you can put it in the mini mash no problem. you didn't list what color crystal (20L/40L/120L, etc) and that matters a bit.
a lot of dark crystal can impart a lot of strong flavors that may not 'work' in the beer. the color and flavor changes as the roast darkens.
if you want to dip into the mini-mash realm, cool, but I'd up your 2 row a little bit. maybe 3lbs of 2-row, mashed with the crystal doing the 'bag' method people talk about on here (sorry, haven't done it myself, but i hear it works well).
can't comment on the hops because you did not list the AA % or the hop schedule. hallertau is a good 30 mins down to flameout addition (flavor, aroma), pretty sure vanguard can be a bittering hop, and cascade definitely can.
My suggestion: hit www.beertools.com
and signup for their free online account, and then input your recipe/ingredients using the "specialty beer" category (since its wide open for style guidelines), and see what it gives you for OG, IBU's etc.
for a first try, and no style provided...it'll definitely be beer. you can't go wrong with a base malt and some crystal, and the right balance of hops. you just need to find that balance using the ingredients you bought.
using 8 types of grain and 4 hops is fun, but a good brewer should be able to make good beer with just a couple of ingredients. exactly like a good chef.
don't feel like you must use all 3 hops in this batch, but if you really want to, by all means do it.