Hello there.

[Frank S]

From the way you are describing what you plan on doing. the garage door opener would already have a sprocket for a #25 chain so you cold probably get away with sprockets easy enough. However sprockets and chain have no slip unless you incorporate a friction clutch in your design to serve as a torque limiter.
With a belt and pulley's these can have a built in torque limiting factor depending on how tight the belt is.
You did not mention the capacity of the trailer jack so it might be possible to over power the jack screw even with a modest 1/3 HP opener depending on the gearing.
the attached file may help you to determine the tonnage required for your sheet metal projects this chart shows the tons required per foot so if you are only making something say 4 inches wide divide by 3 to come up with the force required
SheetMetal.Me – Air Bend Force Chart.pdf

As far as using limit switches this is a good idea just remember there is always an amount of spring back so over bending a few degrees is almost always required different materials have different spring back rates also the radius of the punch factors in the larger the radius the more spring back there will be