Face and fur make the same amount per hour. The bonus comes in for face because there are times when you're in more demand and you can get more hours. Plus, you get more breaks and more show/parade/specials opportunities.
And entertainment (parades/characters/non-equity shows) make the most hourly in the parks over other areas.
Almost all characters and parade performers start as fur exclusively first. Then you can go to "face auditions", which used to happen quarterly (unless there was an extreme demand for a character). They look at you and look at you, hold your picture up to images from the movies. If they think you look like someone, you move on to another round where you get fitted in wig/makeup/costume and go in front of casting.
If they "approve" you, you get trained on mannerisms, voice inflection, autograph, etc.
Most gals are approved for multiples - ie., if you're Belle-approved, you're probably also Ariel and Cindy approved, and maybe Poppins too.
Most Wendys are also Alice, because of height. And for the princesses, they really stick to height.
For fur, you're broken up into different categories that roughly go like this -
4'11-under: Duck (Donald, Daisy)
5'0" - 5'3ish: Mouse (Mickey, Minnie)
5'3"-5'6ish": Munk (Chip & Dale)
5'6-5'9": Pluto
5'9"-6': Tigger
6'+: Goofy