Or can you make a version that's set to 0.9 movement speed instead of 0.8

Can you make it a slider in CBA?

i cant play without this mod

one of the best mods in arma , finaly realism is a thing

The mod is not made to work with other mods or the compatibility, if you have issues, I would recommend to use Remove Stamina.

Ctrl C already defaults you to a painfully slow combat walk, where you then have to hold shift to jog. I also have alternative sprint mod that allows you to hit Shift twice to sprint faster for a bit. IMO, the walking even with gun slung is too slow... like too casual rather than purposeful, but jogging is too fast to be doing all the time in combat... not to mention it appropriately drains of stamina. Carrying a 100lbs of gear you should not be jogging for an extended period of time, let alone fighting that way. Crouched walking should be as slow as it currently is or slower (and more draining of stamina), and upright walking when you're not aiming down the sights should be faster, with the slung weapon being even faster. Adjustable walking mod almost gets it right, but screws up ACE fatigue's ability to stop you from jogging, lets its too fast walking override everything, and sometimes stops working when too much is happening.

if you want everyone to have this affect, it would be best to make everyone load it and the server. If you personally want it yourself, you can use it locally/client.

Is it better to run this globally among clients and server? Or just either.

bruh what

this should affect all of what you listed, every single movement with the player you control will be at the speed of 0.8. This is also applied to AI.

Which stances/positions does this affect?
Gun up vs down?
Standing vs crouch vs prone?
Combat mode vs non-combat mode?