I like ball locks because they fit better in my chest freezer(taller and skinnier versus pin locks). There is no real performance difference so I'd do a little research and find out which ones are more common in your area. In any case you can mix and match them so long as you have connections...
4.5 with my Blichmann Top Tier heating both mash and sparge water in 40F weather and 80 minute boils. Probably closer to 5 or 5.5 if you do 60 minute boils and are in a warmer climate.
That is good to hear. Its US-05 in an IPA and I dump mostly everything into the fermenter so I figured it was the yeast hanging out on all the break material in there.
You'll still need the DME as your base so you need it to be the bulk of your fermentables, go with extra light or light extract(not sure what your LHBS sells). Crystal malts add a touch of sweetness so if you want to go really dry, omit them as cheesydemon3 says. And by sugar/rice/corn I meant...