Let the fun begin !!! ???

[JAZZCNC]

Clives answered the slaving question correctly but I'll give a little more detail.!
When the motors are slaved both move together towards each home switch. The first switch to hit a switch stops just it's own motor not both and reverse's off the switch. The other motor carry's on it's merry way until it hits the home switch and does the same.
Now in practice this happens so fast it appears as one motion. This is because if the gantry is setup correctly the switches should trip exactly at same time.
If your gantry is not quite square you can tweak it square by moving the switches slightly but all the same it still appears like one motion as the difference will and should be tiny.

Regards the Motors and single or twin motors then it's personal thing and close call in some respects. If using quality Digital drives with stall detect like AM882 then I wouldn't worry about it and it's far easier to setup and less messy on wide machines.

One thing I would suggest to get the best from the motors is that you use more than 60Vdc with 80v drives and if using toridal psu you'll easily get away with running 70vdc. The extra 10v makes all the difference and worth sizing psu to maximise the motors.

Regards the electronics then don't get carried away like Eddy current did because for home use it's really not required. YES safety is important and a decent emergency stop circuit is required but you don't have to go to lengths of using expensive safety relays like Pilz. Normal Relays will work just as well if sized correctly.
More important is that e-stop or safety circuit can not be reset unless any fault is cleared and that it removes power to any devise that might do you harm.
Limits I don't really class as emergency stop condition and more positional error so can be dealt with in a differant manner. Instead of killing Power to devices they can just inform the control software limit as been tripped so can halt G-code and at same time remove siganls to the drives by using the drive enable signal.
This should be done in such away that it halts the machine and won't allow reset until limit is cleared or over ridden but at same time leaves the drives powered and holding the motors under torque.
E-stop system should done in such away that it responds to outside events like Fault signals from drives, IE Stall detect, VFD/spindle fault or emergency button press. In which case power should be removed and again system not allowed to restart unless fault cleared.

Building a control box isn't difficult and doesn't need to be complex but it does need to be safe which is easily done using relays.