Balance them again after you move the towers forward.
Subs, well, there's an entire section of this site devoted to that topic. I generally exclude myself from those conversations since I am a hopelessly biased SVS owner

. I will say that it is hard to argue with the value offered by Hsu and SVS for their subs - and I will say that there's no such thing as too much sub

. I would also consider the Axiom EP-500, given the size of your space.
Much depends on on your primary listening source - movies versus music. If it's the former, I would go for lower extension (20Hz recommended) and more SPLs, probably with an SVS. If it's music, I would go with Hsu and I would consider a sealed design (not a must though).
Just to wear my Captain Obvious soapbox hat for a sec-
You need to research this information yourself - don't depend on others' very subjective opinions, especially on forums such as this. There are many very knowledgeable people here, but there are also many folks who sort of function as "repeaters" for opinion sources they have read here and espouse for the sake of acceptance into the fold. Be critical, and be sure that when opinions are offered, they can be defended with objective data.
/Captain Obvious
So ignore me
Cheers,
Matty K.