Hi Owain
Unless she is completely flat-chested, she will definitely need a good supportive bra. I like the Shock Absorber ones (and I'm certainly NOT flat-chested

)
I'm a complete beginner (or at least I was, 8.5 weeks ago

) and I've been doing a run/walk program. I can definitely recommend it as a good way to start. The program I've been doing is in a great little book called "Running Made Easy". As well as the program, it's full of good tips for beginners, and will even take you (that's generic you, not you personally, of course!) up to marathon distance if you're sufficiently inspired.
This is the book.
Anna