Lathe spindle synchronisation, phase A & index - Select suitable Mesa board

Hi,
I have an ASRock Q1900B-ITX with parallel port, CNC4PC C11 BOB & 2no. C3 index pulse cards, for my lathe conversion. The sensors are monitoring a 60 tooth sheet-metal trigger wheel; one tooth notch is double depth; one sensor sees 60 pulses per per rev, the other sees one pulse. I'm particularly keen to have threading and constant surface speed capability.

I'm getting to the wiring stage of the conversion and I'm double-checking whether I could benefit from a Mesa board. My assumption is that the CNC4PC C11 board does not dictate the step & dir pulse timing, while a Mesa board such as the 7i76 is carrying out computation and is less discerning on the PC latency; I could be very wrong with a misinterpretation here.
The 7i76 (seems very popular) appears to me to accept one spindle pulse only, so either not suitable for phase A + index signal or requiring an expansion board; is there a more suitable Mesa board?
I'm toying with several hardware configurations:
a) ASRock Q1900B-ITX, CNC4PC C11 BOB & 2no. C3 pulse cards
b) ASRock Q1900B-ITX, [Mesa FPGA? card XXXX 26-pin] & 2no. CNC4PC C3 pulse cards
c) RPi4, Mesa 7C81, [Mesa 7i76 26-pin?] & 2no. CNC4PC C3 pulse cards
d) RPi4, Mesa 7C81, [Mesa 7i76e ethernet ?] & 2no. CNC4PC C3 pulse cards

I already have a spare RPi4 and the Q1900B will get used on one machine or another, this lathe, a plasma table or a mill that is currently Grbl controlled.

There are several questions here, thank you for reading this far. To summarise my knowledge gap:
i) Do some Mesa cards control step/dir pulse timing while C11 does not?
ii) Can Mesa 26-pin cards connect to Q1900 parallel port, they are compatible?
iii) Is there a Mesa card or combo that accepts both phase A & index signals?
iv) Is ethernet connection to be recommended for EMC/noise robustness?
v) Is the RPi4 + Mesa 7C81 a worthy alternative to an X86 SBC such as the Q1900B?

Thank you to those who provide the wealth of Linuxcnc information her and apologises for me not being able to interpret and apply this to my situation.

i) Do some Mesa cards control step/dir pulse timing while C11 does not?
ii) Can Mesa 26-pin cards connect to Q1900 parallel port, they are compatible?
iii) Is there a Mesa card or combo that accepts both phase A & index signals?
iv) Is ethernet connection to be recommended for EMC/noise robustness?
v) Is the RPi4 + Mesa 7C81 a worthy alternative to an X86 SBC such as the Q1900B?

i) Yes, step generation is done in hardware with Mesa interfaces.

ii) No, Mesa daughter cards need a FPGA card to drive them, rather than a parallel port.
Note that you can drive parallel port breakout boards like the C11 with 25 pin FPGA cards

iii) All cards with encoder inputs can use A + Index

iv) Yes, Ethernet connected cards usually have better EMI resistance.
As a general rule, Ethernet is better when the controlling PC
is not in the same box as the control electronics.

v) the RPI4 and 7C81 are a good solution but might not be the best choice
for a first LinuxCNC project as they will be more work to get up and running
due to their newness.
As a matter of fact, if you have a C11 card and a PC with a parallel port
And this is your first LinuxCNC project, I would start there and only change
hardware if you are running into speed limitations.

PCW,
Thank so much for sorting out my incomplete understanding, in such a clear and concise manner.
I will proceed with the Q1900B + C11 + 2x C3's as you recommend.
Your help is much appreciated.