At this point, no, you don't need to withhold food. And you can test at whatever random times of the day or night you want to. A non-diabetic should stay in good numbers all the time (except maybe at the vet

),
As far as testing, it's kind of up to you. Most folks will drop to testing a couple of times a week for a few weeks, then once a week, and after a couple of months, maybe once every two weeks. I would not ever go more than once every two weeks though. Diabetes can return if she gets into higher carb food (
always research a food thoroughly before changing food, for the rest of her life), or if she ends up with a dental problem, UTI, or any other kind of infection/inflammation. And if it does come back, you want to catch it early and get her back onto insulin as soon as possible. If you ever get a number in the blues or yellows, you want to post here, grab tests for a few days in a row, and make sure that she either gets back into the greens, or gets on insulin.
Of course, I hope you'll still be posting on here anyway! It's been great to see you chiming in and helping other people! That's how this board keeps going.