Replacing bindings

Yes and possibly no. First things first, if you break a binding, go to your local shop and see if they can return it to the vendor. Second if the holes match up you can put it in those holes you just have to put a little metal insert in them I don't know what they're called but they should go in to make sure the screws catch.

Youre fine. You shouldnt need heli coils. Just put some glue in the hole before you screw in your new heel piece?

I would only replace the broken heel, no point taking off the toes and other heel if they arent broken just to replace them with the exact same thing.

Frankenbindings are neat

You will probably need to readjust your forward pressure.

Bumping this. I have the replacement bindings. How should I mount the new ones after removing the old ones? The size is right and I can use the old holes.

did the exact same thing but with rossi axials originally and got px12s as replacements skied maybe 5 or so days on them so far and havent had a problem

Can you use the same holes? Yes. Should you? I wouldn't recommend it if you don't go about it correctly. It all depends on how you go about it and whether or not you know what you're doing. If the old bindings were over-torqued or the holes in the ski are too big (for whatever reason) and the screws can't get a bite, you'll rip the binding out. If you decide to try and remount them in the same holes, you should use a quality epoxy. I've used steel wool with epoxy with mixed results in the past. I've never had bindings rip out using that method, but I have had a couple mounts that I wasn't comfortable sending back onto the hill. If you can't tell a solid mount from an ehhh mount, the steel wool/epoxy or just epoxy method can be a little iffy. If that epoxy method failed, helicoils were used or the bindings were just remounted a bit forward or back on the ski, with the latter being the best option.