spray glue is what i used but with leather its different you need a much stronger glue like contact adhesive, stil with this there is the chance of it coming away, upholsterers usually stitch along the arm rest to make the piece of leather in 2 pieces, therefore it doesnt come away as easily
as for getting the material off the panel is made up of two panels, they heatstake them at factorys, the mushroom shaped bits of plastic on the back of the doorcard with the holes in, these are the heatstakes, what you have to do is remove them by using a dremel drill (best thing to us) but be careful, the trick is to leave as much of the plastic on as possible, so when it comes to putting the panle back together its lines up correctly
once the panel is off there is also the door pull surround to take odd, using the same method, and then rip the material off, its also best to remove the foam thats left, use a wire brush on a drill
then retrim the panel, be patient and get some help
then to put the panel back together clamp up around the heatstakes and use a soldering iron with bits of plastic to melf back around to keep the panel in place, it takes some time but again be patient, for the handle surround i had to use screws and big washers to attatch it back on as it kep falling off, was only on one side though
i am going to get a guide done at some point