I'm not sure I know what you are pointing at? But, the bridge connects to the two loops you can see pretty clearly in the pics above above. The stock bridge is designed offset so you girth hitch it on one loop and use a carabiner on the other. I swapped out stock for two small runners which I use that frees up some space, but also prevents you from canting (you'll see those orange runners in the pics). I like this because I use a xbow and don't really want or need to cant. But, if you use vertical you might want the flexibility (or xbow you might want it too). I would stick with the stock bridge for a while and see how you like it before you start changing things up....
Google Eastern Woods Outdoors.
No. I dont think it's easy to put layers on in the tree. It can be done (top half only)....and I do it....but not easily imho. I'll put on all layers except maybe one at base of tree. If this is a big deal to you a minimalist saddle may be a better choice.
Its probably easier if you stick with the stock bridge. I've shortened mine. With stock you'll have more room. Play around....might be easier to put on while you're standing on your stick and have LB on....before you attach tether and bridge and sit down. I have alot of presets so I dont sweat too much while climbing....maybe others can chime in
