Yes, kefir is very good. I have some kefir grains and make my own using raw milk.
Tiffany
I wouldn't do the yogurt until at least day 4 when you're ready to incorporate dairy. Dairy is hard on the digestive system for a lot of people.
There are powder probiotics that you can mix in liquids and drink. They can be found in the refrigerator section of the healthfood store. I'm not sure how they taste.
Tiffany