Hi.. and congrats your decisions. Just walk at first to build up your stamina. You don't want to do to much to fast. List to your body it will tell you when to start adding to your workout.... Good luck!
Yes you can take Biotin. You also need to check your protein. Make sure you are getting enough. I don't know how many grams your Dr has you getting in. I know take in a min of 60 gms a day .