Okay my daughter is going to be 4 months old July 31st. I know the time is coming to start her on solids. but im a ftm and I have questions!

1. When do babys start solids? I've read 4 months and I've read 6 months.

2. What do babys start on? cereal? oatmeal? both?

3. Can I use my breast milk for the cereal and oatmeal? or would it be easier to use formula?

4. Do I start giving her a little water when she starts food? I read you do but I've also read it's bad for babies to have water?