I really wouldn't worry, I personally feel all the pain and blood apparently caused my first time sex is dramatised. When I lost my virginity my hymen did tear and I did bleed a bit. It wasn't a great amount, especially considering it's not just blood as it's mixed with natural lubricant and sweat. Also it didn't really hurt either, it was more uncomfortable than painful. My best tip is to just make sure you are well lubricated.
This is why I am worried about first time sex! My boyfriend REALLY wants too but I am just not sure.
Maybe. It depends on the woman.
You bleed because your hymen gets broken. Some women's hymens are already broken before they have sex. This maybe due to them not having much of one, accident, surgery or tampon use.
Also sometimes it depends on the angle of sex as some positions allow deeper penetration so sometimes the hymen just stretches more and it might break at another time of intercourse.