So, Deadpool was given his abilities, meaning he didn't always have them.

That begs the question, if he was circumcised at birth, would he somehow regenerate his foreskin after gaining his powers or would since everything's long since been healed, would he not regain his foreskin because there's no broken skin or open wounds to heal?

I guess the SFW version of this would be "Would an amputee that's been an amputee for a long time and thus they have a stub with no open wounds suddenly regenerate their amputated arm after getting Wolverine/Deadpool's healing powers?"

I don't know why, but I need answers.

It doesn't heal Deadpool's skin, so I suppose it's set afterward. Sort of a double-edged sword for him. I think in the comics, Deadpool still has cancer, as his healing doesn't get rid of it, it just keeps it from killing him.