Adrian,
Here's what you need to protect your piano from humidity extremes:
http://www.dampp-chaser.com/I've had Dampp-Chasers installed in both of my pianos for years, and I recommend them to all of my clients. You'll find that you need to tune the piano much less often, which is better for the pin-block, since after so many tunings in its lifetime, a piano will often need to be rebuilt using larger tuning pins.
Fran is absolutely right about concrete floors sounding good for grand pianos. Plus, you'll want to be able to roll the piano around to accommodate various miking scenarios (you should have the piano mounted on a piano dolly, by the way, to reduce the stresses caused by the three legs moving independently when you roll it around).
Congratulations on your piano purchase.
--Wes
