This is actually a Super Power so it has 4 bottom holes. Personally not a fan of the Proton Power as its a little too narrow (but still have one...)
Stung in sidewall as it holds up to the weather better. There's a great little trick you can do by slitting the leather and then putting a piece of sidewall through it. Jay has done this with an Easton stealth as it doesn't even have traditional bottom holes.
Yes you need to make a little slit in the leather and the feed some side wall or cross lace through it. You can either knot it so it doesn't slip through, or you can loop it through. You can then tie the string into the bottom of the head like a bottom string.
With a proton power you can also feed a sidewall through the bottom sidewall holes and across the bottom of the head giving you an anchor to tie to. You can either feed two leathers through the bottom holes or do all four in the same way on the anchor line. It's never going to be quite as strong as traditional bottom holes but is a very good option.
I've also seen proton powers where the outer leathers are tied round the last sidewall loops at the bottom, as the head goes so thin it doesn't look out of shape.
The slit and sidewall trick is what made the Gripper Pro pocket illegal. http://www.laxrules.co.uk/?p=1461 But on the other hand it's something Gary Gait used though if I recall correctly and it seems to have worked for him OK. You could even loop the string through the bottom hole to catch two leathers. I've seen someone tie a piece of string across the bottom from the last sidewall holes, and if done tightly enough should result in two extra openings on the sides of the ballstop that you can feed the leathers through.
It's really cool how these heads still are on top while others come and go. Evo, Clutch, PP, Edge. So much to choose from, but these are still some of the best out there.
I think I still have some special poliester string that should hold up in the rain much better. Care to try it out?
I like to string and I like to help my fellow stringers. Drop me a line if you need help, be it stringing mesh pockets, custom pockets, repairs etc.