The bracelet is pretty easy to size if you have an eyeglass screw driver (and for what you pay to get it resized you could buy a set). Just remove both screws per link on the pro2 bracelet and pull the link apart, reassemble in reverse with however links out you need removed.
The "Keeper" is the little circle of leather that holds the long end of the strap. The pictured strap has 2, one is removable one is not. I have the integrated strap on my po and it has no keepers because on the omega clasp the long end of the strap goes under the deployant not over like the hirsch. The hirsch clasp would be perfect for that strap though.
3 issues with that strap on deployant, 1. you dont want a band with a fixed keeper, 2 you'll see the notched cutout for the buckle, 3 the strap holes are way too large for the deployant and wont be held secure... 4. it may be too thick to fit in the deployant well.
I just swapped the movement on my 219, it was a member purchase and arrived broken (center wheel/cannon pin). It really wasn't that bad but the 219 had the dial feet ground off and no dial dots, can only assume thats what broke the cw. Hands ended up working fine even though I bought a 111 set based on seeds posts. Used dial dots to secure the dial and its working great.