Questions on legally adding Square Footage/Code in Seattle?

[Charlotte Casey]

Hi, I would so appreciate some insight:

If you add a window that opens to a room that already has a closet and can fit a bed (but was never counted as a bedroom) can you then count that as a bedroom and change the house from a 4 bedroom to a 5 bedroom?  Does it have to be a particular window or just as long as you can escape/egress?  And how do you do add that bedroom legally with the tax department?

Also, if you remodel an attic and want to add all that square footage to the house's records, is there a rule that only the percentage of the attic that you can actually stand in, counts towards square footage?  I thought there was a rule about 7 foot ceilings?  So the attic will be about 1200 sq feet, but with attic, sloped ceilings.  Can we count the whole 1200sq feet or just a percentage?

Thanks!