The Axe module works exactly as we want it. It is a choice between two things - how it is now, or having it work on EVERYTHING that an axe works on. This includes chests, and random things such as IC2 cables. We received a bunch of complaints about people busting their chests or wires unintentionally so the change was made to only affect trees. It is the safer path.
As for the second thing, I'll look into that but cannot give any guarantees.
I'm not doing anything with horses until we are 1.6... still doing 1.5.2 right now. As for the second one, I do have a backpack module planned but it's going to take a while.
Balancing this would be very difficult because I don't play any of those mods anymore =/
To be honest, that's probably really complicated and out of my coding league. Otherwise I would do it.