K.G.
Yes you can use NFP while you are BFing! It can be a little tricky but it is possible and NO you do not need to use condoms while BFing! Most of the time a BFing woman will have a "warning" period before she starts to ovulate. I have BF all 3 of my children and use NFP. I start to watch for cervical mucus when the baby is about 6 months old. As mentioned you need to watch for stretchy or clear egg white mucus. this indicates that you are ovulating. After you mucus patch you need to have 3 days of "drying up" before having intercourse. I know that this sounds really complicated but it really is not!
You should also keep in mind that alot of bfing mothers do not get thier fertility back until they are done nursing. I have known women who have gone 18 to 24 months without thier fertility!
Please check out ccli.org They have alot of good info. You might also want to lookinto talking an NFP course. My husband and took one before we got married and really enjoyed it!
Blessings, K.