6040 CNC retrofit

So, I dug out my 14-year-old 6040 CNC again. 
I already retrofitted that thing once, tossed almost all the original electronics and went with G540 and some old industrial PC. Still, I was strapped for money, and it was a hack. I only used it occasionally for a couple of years, then it just collected dust. 
A few months back, I found myself in a situation where I had a lot of time, and I'm no longer that strapped for cash either.
I got myself a new set of closed loop steppers and CL57T drivers from SteppersOnline, MESA 7i96S board, proper PSUs, a new mini PC and nice steel enclosure, and I'm trying to push hard to do it properly this time. I have a physical layout somewhat complete but still grinding the schematics.

Would somebody be so nice as to look it over?

I have the following questions:
1) Is it ok to use 5V to enable stepper drivers (OUT0)? Stepper drivers will be configured to use 5V, but I'm assuming that DIP switch is only for STEP/DIR pins.
2) Since I'm feeding 24V to IN COM, I have to use 24V to detect alarms from stepper drivers. Is it ok to mix 24V and 5V on the same driver for different functions (5V for enable, 24V for alarm)?
3) Can I detect driver alarms with just one input? Any practical benefit have them wired individually?
4) Right now, I have all limit switches wired independently, but I really need that? Current setup has them all in series on a single wire. Is there any practical benefit of having the wired separately?
5) Not sure about E-Stop. In the schematics, it kills the VFD power and sends a signal to the controller. But I'm not sure about that at all.
6) I have two input pins left, but I still need a probe at least. Am I missing anything else? 

Thanks a lot for any suggestion.

1, I set up a number of these drives about a year ago, going from memory, the 5v/24v switch is only applicable to the drives step/dir pins. I am pretty sure I used 24v for the enable input and the error outputs.

2. see #1

3. You could combine the alarm signals, but then when one alarms you won't know which one without opening the cabinet and looking at the drive's leds.

4. With the drives homes wired independently you can do simultaneous homing. With limits separate you can tell which joint is on which limit. (Sometimes this isn't obvious if multiple motors are close to their limits or if you have a wire or switch failure.)

5. ? There's more than one way to do this. But I usually had both an estop out and in to the control to include in the loop.

6. You only need one input for a probe.