1 - Yes this is possible, it is explained in detail here
https://www.assettocorsa.net/forum/...ere-check-first-post.12249/page-4#post-716251 I think you may need an account if you haven't got one already.
[SPEED_INDICATOR]
ZERO=0
STEP=1
MIN_VALUE=0
OBJECT_NAME=ARROW_SPEED
OBJECT_NAME_MAX=
ZERO and MIN_VALUE are what you need to set up.
2 - You would just use another dummy and set it up separately in the config as you would any other gauge. EDIT: If they are both doing a variation of speed then I am not sure, sorry I did not see that it was also speed when I first looked.
Another Edit:
You can set up as many dials as you want if you are willing to use CSP config for them, it's all explained in the wiki:
Configuration files for Assetto Corsa Custom Shaders Patch - ac-custom-shaders-patch/acc-extension-config
github.com