I am in the process building a CNC (Grizzly G0704) around the MACH3 software. We purchased the Grizzly and the MACH3 but I need to take it a bit further for the automation than the company we purchased the base machine from. I need to understand how to add the limit switches through MACH3 , making a new screen for the operator and controlling 2 outputs for a 24vdc valve plus 3 inputs for sensors. If someone would like to do some phone support it would be greatly appreciated. I could possibly pay a small fee for the help.

It is hard to give specifics of how to add switches unless you can say what electrical/electronic hardware you have, a link to documentation would be even better.
Screens can be edited with the screen editors available, there is a learning curve but there is a section on the forum for screens and also there should be a video or two describing the basics.
 the need for 24v outputs would likely require you to use relays, but again unless we know what hardware you use no one can really advise.

Hood