"Is it even better for a Christian man who experiences sexual attraction towards boys or youths to refrain from any friendship at all?"

I don't see the Scripture teach in any place that we are to avoid people to whom we are attracted. Men are nowhere taught to avoid women or not befiend women and visa versa. Scripture teaches that these relationships need to have apropriate boundaries and we live how we need to in order to live within these boundaries.
I suggest that the best place for any relationship is within a community setting. If you are spending time alone with someone you are attracted too then obviously temptation and opertunity will increase. But even then you can still exercise self-control. However, if your boy relationships are within a communal setting where there are plenty of other adults and kids about, I see that as very heathy.
I think the idea of punishing ourselves because we experience sexual attraction is not a Scriptural idea.

"Should a Christian man seek to establish a close relationship which may develop into an inordinate affectional bond, which is not supported by the scr iptures?
With any weakness that we experience due to our fallen nature, should we move closer to our area of weakness or further away in order to reduce the possibility of falling into sin?"
Assuming that we shouldn't move closer to our weeknesses, the question then is 'what is our weekness?' To say that boys in general our our weekness I think is going to far. To say that a close relationship with a person is an area of weekness is also going to far. A romantic relationship or a sexual relationship would be crossing the line, but a strong friendship that stired romantic or sexual feelings, as long as it stayed only a strong friendship would be no more than a strong friendship and would not be sinful. The sin comes from ACTING on unholy desires, not from having them.
I don't think it's right to compare a boylover being with boys to an alcoholic being with beer. The reason is that a boy is a person and a beer is a thing. We are called to be in loving relationships with persons... we are not called to love things.
If we have a relationship with any person we will be increasing our chances of sinning. We will be increasing our chances of getting impatient, angry, selfish, neglectful, rude, speaking negative things, foolish joking, course talking, criticisms, stealing, adultry, murder and almost any other sin. This is never a reson to withdraw from people on our quest for holy living. Rather we take on the fruits of the Spirit (Gal 5:22) love, joy, peace, patience, self-control, kindness, gentleness, goodness and faithfulness and let these make our relationships holy and healthy.

Blessings
Cat.