Thanks for the feedback!
To answer your questions, Kenobi is about 35, and Anakin/Carima are in their mid 20s. Episode I takes place 28 years prior to ANH, II is 4 years after that, and III about 4 years after that. Making Kenobi about 60 come A New Hope, and the unmasked Anakin about 55 when he's unmasked in Return of the Jedi.
Carima and Anakin are indeed a couple, in the course of the film they get serious about their relationship and decide to get married at the end of Episode II.