As somewhat stated already in previous posts... abortion is not about the rights and obligations of parents. Those come into play after birth.
The core argument for abortion is that a person has the right to full autonomy over their body. It just so happens to be our biology that women get pregnant and men don't. That's just the way it is, whether we think it's fair or not. Therefore, women are the only ones in a position to be able to decide whether they want to have an abortion or not. Neither the biological father, or any other person in the world, should have the right to decide what a woman wants to do with her body.
On vasectomies ... I had mine a couple of years ago. The doc did ask me if I was married, which I am, and then asked me if my wife was in agreement with me having this procedure done. I told the doctor "Yes, we talked about this and she is in agreement, but I don't see how that's relevant. I'm having a procedure done on my body and it's my choice." The doctor was surprised to hear this. He did say he agreed with me but that he was required to ask. Anyway, my wife didn't have to sign anything, much less be present during the procedure so apparently it's not required here in the UK.
With regards to parenting and child support ... I'll come back and post later today as I don't really have the time right now and this is a deeper, more complicated issue.