Hi Mkvxg,
That’s a lot of questions in a few lines 
But let me see what I can do for you.
You use either USERSTOREKEY or USER and PASSWORD. I’m using USERSTOREKEY. In my sap_hana.cfg it looks like this:
USERSTOREKEY=DHE_MONI
SID=DHE
So, that is each entry on a new line, no delimiters etc. If there’s more than one SID, I honestly don’t know.
The userstore (and user) was setup by our HANA administrator so I don’t know what rights the user has. However I do know there’s a MONITORING role in SAP HANA, so you may want to start there.
I’ve set mine to use RUNAS agent. Don’t know the difference, but in my case that works. So, my whole sap_hana.cfg looks like this:
USERSTOREKEY=DHE_MONI
SID=DHE
RUNAS=agent
If you’re facing issues with the plugin logging into the HANA database you may also want to check out this post: Monitoring SAP R/3 + SAP HANA
Good luck,
Louis