Apple wireless BT keyboard with TEXT MESSAGING iPhone

I know that I can sync the Apple wireless bluetooth keyboard with the my iPhone 4, but I just want to verify that it will work with text messaging, in addition to the usual email, etc. apps. Frankly, thats the main reason I need it. I messed up my elbow from texting so much. I dont want to, but I MUST text a lot, so I figured Id get the keyboard to save elbow injuries. Sounds silly -- lugging around a wireless keyboard in order to text... but it actually wouldnt be so bad. I do a lot of texting from my house, anyway.
One more thing -- The wireless keyboard can only be paired with one device at a time, right?
3.0 GHz 8-core Intel Mac Pro Mac OS X (10.5.8) two 17" Apple Monitors w/DVI-ADC boxes, PCIe USB hub, Digidesign 002R /Command8