You will also have to enable the soft limits, I use my own screenset but there should be a button below the DROs on the main page which will enable/disable the soft limits. When you have them  enabled you can jog any axis and if it stops before it hits the physical limit switch you know you have the soft limits set up right, you will also see a message saying "Softlimits, movement aborted" or something like that.
 First of all you need to get the Y Axis travelling in the correct direction, on your setup + is away from you as in your pic earlier in the thread. If its wrong change the low active in motor outputs. Once you have that right then try changing the Home Neg in homing/limits page.
Hood

BTW the low active I mentioned in the above post is for the Dir for Y axis in config>ports and pins>motor outputs page

Hood

OH - ok, if Y+ is away from me then I am in good shape. Let me check soft limits and make sure they're OK.
Boy this has been a great learning experience. All newbies like me should read this thread!!

When I watch the Mach3 videos it is apparent that when the demo machine is referenced to home, it shows that to be in the lower left corner of the table area.

My limit switches put my machine home at the top left of the table area. Consequently when I load the roadrunner program and jog my table somewhere in the middle of the table area to set a x and y zero starting point, the display shows my location (the brown crosshairs on the display) BELOW my table work area (the red rectangle).

Since my home position has to be top left, how do I compensate for this coordinate difference?

Your home position is best set up lower left as in the video, you should be able to change this by ticking the Home Neg options for X and Y in Homing and limits page.
Hood

Does that not require that I move the limit switch to the nearside of the y-axis table travel?

OK maybe I am misunderstanding how your limits are set up. You have a single switch on each axis, correct? Does the switch get triggered when the gantry travels to either end of the table? If so then your single limit is acting as both a +ve and -ve for that axis. If the above is correct then Homing Neg should make the gantry travel in the Neg direction to home.
Hood

No - unfortunately the limit switch only activates when the y axis moves to the extreme upper end of the travel. Limit switch is attached to the machine frame rather than the moving spindle assembly. I should ask K2 about this... I'm sure there's a work-around

Would be better if you could move the switch onto the moving part of the Y axis and trigger it at either end by a raised block/ramp fixed to either end of the the gantry. This would of course pose the problem of the wire needing to have enough length to reach the extremes and some means to keep it clear of the moving parts.
 You may have another option, do you still have an Input pin spare? if so then you may be able to rig up another switch.
Hood

Good idea. I'm also waiting for feedback from my contact in K2 CNC. I'll update as soon as I hear