Yes, the holes are so I could add a bungie cord loop (with braided leather tab) to make a "hammer spur strap" in the future. From a tactical standpoint, I'm not a fan of things like that but from a "snazzle" standpoint in an open carry holster . . .
I have made several other holsters and the body of this one is basically a direct copy of others I've made. There's not any problem with the gun tipping because there's enough slide weight lower down.
I've "gone heeled" professionally for decades and want belt slots sized exactly to the belt width so there isn't any slop or movement when drawing. The holster is molded and fits snugly for retention. The placement of the strap was determined by aesthetics so I ended up with a 2" belt tunnel. One thing that did concern me is the width of the belt tunnel. It's about a half inch larger than the belts I wear for carry. So far, there hasn't been any problem with the holster coming up with the gun during the draw stroke but I would watch out for that with this design.
Of course now I HAVE to make a matching belt . . . and mag pouch . . . and cell phone case, and key fob lol.