Hi my name is Robert...
I have to agree with Randall on holding the selling dealer accountable but maybe I can point you in the right direction on some of these items, first off did you get an owners manual? IF not I can send you one.
1.. Normally on the jacks if the alarm is going off when the jacks are up it can be caused by low hydraulic fluid in the tank, as the jacks retract it pushes the fluid back into the tank, as the fluid goes back to the tank it raises a float switch. I would check the fluid level in the tank, run the jacks and listen for the pump motor, the tank will connected to the pump. It will take Dexron fluid and the level should be near the top right below the fill port.
2....IF you have an electric seat look for some wires under the seat, sometimes you will find an inline fuse, and the wires might have a shield over them. IF not look in the chassis box outside under the engine access for a fuse.
3. The short could be a loose dirty connection. On the pace arrows I have seen there is a fuse box under the outside access for the engine under the drivers side dash, that would be a good point to check all the fuses and breakers inside that box, make sure all the connections are clean and tight. Normally you would have three fuses boxes, one for the interior items and that would be with the breakers, that box could be under the fridge OR on the base of the bed. The RV manufacturer will also have another box outside under the engine access and then you will have another chassis fuse box that the chassis builder put in. IF it is a FORD then the dash pod will swing up or have a few screws you can remove and the fuse block is on the top. IF it is a GM then normally the fuse box is in front of the steering column on the firewall..
I might look at what you can and then have a mobile service or shop take a look. Hope this gives you a little bit of direction.... Robert