Is some slight fetal bleeding normal or is any amount a dangerous indicator?

Depends. It is typically normal to have a little "streaking" but anything more should at least have you alert your OB and ask if you need to be seen for examination.
Depends. Technically bleeding during pregnancy does not typically come from the fetus. Usually bleeding during pregnancy comes from the cervix or placenta. 50% of all pregnant women will have some bleeding in the first trimester. Bleeding in the second and third trimester is more concerning and should be evaluated immediately.