Is habitual masturbation an impediment to the priesthood?
Yes.
It's one of the things your spiritual director/confessor will talk to you about, with regards to discerning your vocation.
A certain level of virtue (not complete perfection) is required to be a priest. Remember, the priest will have to lead OTHERS on the way of salvation. He will either bring a bunch of others with him to hell, or a bunch of others with him to heaven.
Imagine if your local priest had the problem you describe. Imagine if he started flirting with women, installing hidden cameras in the bathroom, or filling his computer with pornographic material to facilitate his "habit"? Think of the damage that would be done -- the scandal that would result -- if any of these things became known?
The fact of the matter is that sins of the flesh are the WORST when it comes to addiction and how much they control your life. If a priest is addicted to this sin, he is unmortified and that is the precise OPPOSITE of what a priest's life is about (a life of self-denial and sacrifice).
If a priest is that unmortified and addicted to pleasure, there is no limit to the sins he will commit to serve this habit (rather than God). He will compromise on the Faith (to get a larger congregation, with more women!), he will destroy families by having affairs, he will manipulate in the confessional, he will scandalize the Faithful, he will want MONEY to help serve his habit, he will stay in his rectory alone (for obvious reasons) and won't want to hear confessions or make sick calls, plus countless other evils.
The Church doesn't want another priest so bad that it's willing to consign a few hundred souls to eternal perdition!
Matthew
(Forgot to click the box)