Hi,
That's right, it's hard to give an exact figure but I always use 28% as a rule of thumb. I almost never pay more than that in tax (includes Federal Income tax, Social Security, Medicare). And right again, there is no state tax in Washington.
One other tax to account for is property tax, which you are liable for if you buy a home. Looks like the rate in Washougal is $14.22 per $1000 (so $1422 per year for a house of $100K). Note you're not liable for property tax if you rent.
To get an idea of the cost of homes, I'd head over to
www.realtor.com.
I don't think you'll find much in the way of public transport in Washougal. But I'd have a look at the City of Portland's public transportation, maybe they have buses the reach out that far.
The Gorge is a beautiful area. If you're a windsurfer you'll have found your promised land.