Making mill linuxcnc some questions.

Hi helpful people. 

I am looking to convert my cnc mill to linuxcnc.

it's a basic setup. 3 axis, 3 home switches, steppers and DC brush spindle.

There's a couple of things I'm not sure about. 

I have an index signal from the spindel and would like it to have feedback compensation. As it's it's old DC brush motor it tends to drop a lot of RPM and so you have to guess how much over to set the rpm. Especially at slower speeds. 

Can I use just an index input to get the rpm? As I see all the documents on this referring to this on lathes so has a disk with lots of slots as well. I have a lathe project so that's of interest but not needed for the mill. 

if I can get the rpm from just the index can I have linux cnc adjust the output to maintain the rpm under load? So when it slows when for example drilling. It will turn up the power to compensate?

Second is, can I install a second parallel port to connect an mpg? Or what do you use to connect an mpg?

Thanks. 

 

That's interesting.

What kind of puls frequency can you get from the PP. I'm going to use that at first as it's the cheep option to test everything.

Also what's considered high latency on the PP? 
Thanks.