Hi,
I have used Mach4 and an ESS for eight years, and the combination works well.
You have a requirement for a number of inputs and outputs. The ESS has 51 IO's and a UC300, another capable and cost effective Mach4 ready motion control board has 85 and a PoKeys 57CNC,
also capable and cost effective has 57. Any of these three boards would be ideal. Both the ESS and UC300 require, or at least benefit from a breakout board. It is true that you can use very simple
and cheap breakout boards but they will probably require some additional circuitry to get all the features you want. If you are not put off making a few simple electronic circuits then they are very cost effective.
If however you want a complete solution without you having to make any extra circuitry then the MB3 (for the ESS) or the UB1 ( for the UC300) by CNCRoom are a good choice, although being somewhat
more expensive, at around $200.
https://cncroom.com/en/
I have used simple bi-directional breakout boards before (MB2's from Homman Designs in Australia, and no relation to CNCRoom despite the same part numbering!) with a few additional components for spindle control.
My new build mill uses servos and so I decided to make my own breakout board, having exactly what I wanted and nothing else. Attached pic which includes the ESS the green rectangular board atop my
breakout board.
I rather suspect your remote pendant won't work with Mach4. In order for a piece of hardware like a pendant to work with Mach4 it requires a software plugin that adapts the hardware to the Mach4 interface.
I suspect your pendant has a plugin to adapt it to Mach3 but there are few manufacturers that have taken the effort to develop Mach4 plugin. What brand is it?
Craig