What kind of rear brake light bulb do I look for?

Look in http://www.acuralegendwiki.org. They have all that information. Most of the light bulbs in the Legend are fairly standard. Now, the front lower turn signal lights, those are sort of unique. Anyways, remove the burnt bulb and take it to the store, those are easy to remove and fairly cheap.

recently replaced my brakelight bulbs and they were 2057 size bulbs

If you take the blown bulb out the part# is on the socket. (Make sure to put the right bulb back or the "brake light out" will illuminate.)