Hi Kristen

Welcome back!

I can't give you advice about a bike, but with regards to riding: just get out there and do it. Don't worry too much about distance and how many times a week for now. Go out and ride around the neighborhood, and when you feel stronger go a bit further, etc*. Go out every other day, or when it's sunny, or even if it's not. Just do it, as they say. Make it a habit. Then you can always come up with a training plan...

Cheers!