Look closely at the whole latch and you will probably notice that where the hinge attached to the body, there is a bracket (see picture below) and that thing is probably ripped out or is starting to crack. You can by an original replacement bracket for around $20 from various sources and will have to remove the old one and weld a new one in. The other option us to use a J-west manufactured kit that you can find in the resources section of the club. It's a different design that is bolt-on with some drilling required and it replaces that whole bracket.
THe horn electrical system is pretty simple. If you press on the steering with the ignition on and can hear a clicking, then the relay and contact point at the steering are fine and probably the horn is dead or there is a short from the relay to the horn itself.. If nothing happens, then you have to check if the fuse is good, if the relay is working (the relay is under the fuse panel, so you have to remove both philips screws to get acces to it). And you need to check also the contact on the steering, for that you need to remove the center pad by simply twisting it counter clock-wise.
It would be best if you worked with some electrical diagrams like
these.