Winterberry (Ilex verticillata) spacing questions

I'm going to plant some winterberry this Spring and want to make sure I have enough to fill in the area where I'm putting them. I'd like them to provide some good cover in the Spring and Summer but don't want them too crowded.
How closely can I space Ilex verticillata 'Winter Red' without crowding their natural 'habit'?

And I've read a couple places that I should plant one male for every five female plants.
How close does the male (Southern Gentleman) need to be for successful pollination?
Do I need to plant 'him' right in there with the others, or will pollination still be successful at a distance of 20+ feet?
(And not to get too obsessive, but does prevailing wind direction, etc. make a difference?)

Inquiring minds. . .
Thanks for your help!
Teresa

Teresa, the ones here in the wild are right on top of each other, so I would assume that your spacing should be enough for them to have comfortable root space. Theres a little wet hole not too far from us where they grow and they are quite close. In my yard, I have planted the male and female on opposite sides of a fence post, but I've read with other hollies that if there is a male within a quarter of a mile, pollination will result. My daughter has a female holly in her yard and has never seen another in the neighborhood, but has berries regularly.