Is there a cord on the disposal now? Mine came out of the box with a cord with plug on the end.

You'll want the disposal on a GFCI. What I have is similar to yours. Wire from panel to switch, switch to gfci outlet, disposal plugged into outlet. [alternatively, you could use a gfci breaker].

You are confused with just the white wire? Not the others?

At switch, connect the whites together; connect the grounds together and if your switch has a ground screw connect it as well. At the disposal end, should be black-to-black, white-to-white, ground-to-ground. If using an gfci outlet, that is on the 'line' side, not the 'load' side.

I like using an outlet as you can easily disconnect the disposal from under the sink and nobody will flip the switch by accident while you have the plumbing apart. Plus you won't have naked 14-2 NM just hanging under your sink going directly into the disposal. That wouldn't be good.

The ones I've seen don't have a cord (but provide instructions for adding one if you care to). I put a cord on mine and then you can use an "air switch" between the plug and receptacle to operate it. Just drill a hole in the countertop for the button.

I was under the impression that GFCI wasnt necessary to have under the cabinet. What i read seem to indicate that the GFCI under the cabinet would be a pain to have to reset and since it wasnt necessary to just not do it. I appreciate the info and will continue to look more into the GFCI outlet if i put in an outlet.

I was mostly confused on the white wire but am happy to take any and all advice about wiring everything.

If i understand correctly the first box with the switch in it should have 4 ground wires.

Wire 1 - Incoming 14/2 from panel
Wire 2 - Outgoing 14/2 to disposal or receptacle
Wire 3 - additional copper to green screw attached to metal junction box
Wire 4 - additional copper to green screw on switch.

Wires 3 + 4 i will be adding. All 4 wires need to be connected together via a wing nut.

Can i just wrap wire 1 around the green screw prior to joining it to wire 2 to eliminate wire 3?

I was going to use the whip instead of leaving the exposed romex. My main panel is 10 feet from my kitchen so i figured i would just turn off the breaker to the disposal if i ever needed to work on it.

RE: GFCI That might be a NEC2014 change. I remember that in a Mike Holt presentation.

The Insinkerators I've installed do not use a 'whip' or a cord. There is a metal cover over the connection point. There is a 'standard' 1/4" hole that can hold a cable clamp you get from the store. White to White, Black to Black. There is a ground screw under the cover plate. That's it.

In my case, the NM comes out of the wall, no box required. Is that what you mean by the cable hanging inside the sink cabinet?

Your choice using an outlet. Personally I wouldn't bother.

Take a look at panel #6. You can see the cover plate and the cable clamp.

Here is a link that might be useful: installation