Interesting project Jim! For reversing the winch motor direction, perhaps you could also consider a self-centering, three position, double pole, double throw toggle switch. They are spring loaded to the center 'off' position, which would give the same effect as using two separate momentary contact push buttons, but control would be quicker, due to you not having to remove your fingers from the switch to change directions.
Here is a 20 amp switch that works exactly what I describe, and it's cheap!
http://www.allelectronics.com/make-a...MENTARY/1.html
As for your cables getting wrapped over each other, at the place I work, we use an exact winching set-up like that to exchange rolling pallets on one of our cutting lasers. Here's the thing with that type of winch system. The cable will naturally walk one or the other, as it pulls either direction. You can't force it to stay in the center of the drum, or it will begin to cross over itself. The cable needs freedom to walk from one end of the drum, to the other, depending on the direction it is rotating. So with that said, you need two things to make it work well.
1) Your drum needs to be long enough in length to allow the cable to walk freely from one end to the other, and this length depends on how much winching travel distance is required. The more travel you need, the longer the length of the winch drum.
2) You need some means of adjustment for the winching drum alignment. This is tricky. Ideally you want the cable to 'walk' from one end of the drum to the other, at the extremes of it's travel, as it winches. This means the cable should be centered on the drum, at the exact halfway point, of the total distance traveled by whatever the winch is moving. To put it another way, if you have 24" of total winching travel, at the 12" mark (halfway) the cable should be close to center on the drum. At 0", it will be at one side of the drum, or the other. At 24", the cable will have walked to the opposite side. Hopefully that makes sense.
Now the adjustment for alignment purposes is important because if your cable is not centered on the drum, at the halfway point, at one extreme, or the other, the cable will walk itself clear off the drum. You need to be able to adjust (skew) the drum along it's parallel axis, so that the cable stays within the limits of the drum. If the cable is running more torward one end then the other, the whole winching drum (and motor) needs to be skewed at an angle to encourage the cable to stay within the bounds of the drum, and to correct for the point at which the cable stops at the ends of it's travel. We adjust this on our system with jack bolts, which changes the angle of the drum, in relationship to the cable. More angle will encourage the cable to walk more one way then the other. It's something that you really need to play with to get it all dialed in. To much angle and the cable will run off the drum at the extreme.
I hope this will give you some ideas to try. It's something that is easier to show then to simply explain, but I'm hoping you can understand what I just typed!