I passed the WA state exam on the first try. While it's not hard, there is quite a lot of arbitrary information to remember. Did you take the Rockwell course online? That's what I did and to prep for the exam I just took and re-took the chapter tests, going back to study the parts I scored low on.
As far as brokers...really you should interview at each one to get a feel for the office/ broker and to find out the specifics of what they offer and charge.
I'm not with Windermere and never interviewed with them so I don't know this for sure, but I believe they have a pretty hefty desk fee. I can't imagine starting with a large monthly desk fee. Unless you know you are going to have a lot of business to start out with, I wouldn't advise going with them or any company that has one like that.
I've seen the Newberry office in Kent, but I have never seen one of there for-sale signs out...ever. Maybe they are more specialized in Kent, but I think to start out with you might want a company that has a larger share of the market.
John L Scott and Windermere have a large share of the market here, but you have to remember that they are regional companies only. Prudential and Remax are national companies. I have seen commercials for Prudential, something I have not seen with the regional two.
Again, your best bet is to go to each broker that you are interested in. Get a specific break-down of what your costs with them will be, as well as what kind of commission split you'll receive.
Good Luck!