Hi! Can you please tell me how much of an area does a 9,000 BTU cover from an air conditioner (portable unit)? Thanks

Portable, as in hose out the window? I've seen but not worked with those, but going by cooling btu's 300 sq ft has been bandied about. In my experience you could get two rooms comfortable with a 9k AC.

Check this:
http://www.feddersoutlet.com/sizingguide.html

Their 7000 BTU model is recommended for one room 12.5' x 20' (250 sq ft).