I am struggling with this myself. You can use CoreRPG to create a dicepool on the charactersheet itself. You can setup with all the stats on it, and drag/drop onto a dicefield to generate the pool. It is clunky as hell, and I wish to god, that the NPC sheets were the same as chactersheets. Alas they have basically no functionality, so I am considering just using charactersheets for npcs.
Here is a link to the template I am currently using:
https://www.dropbox.com/s/m670icfwc5...plate.xml?dl=0
As for the community ruleset. I do believe that such a thing could be made and released. You cannot copyright gamerules, only content. Sadly I doubt it will happen, since MHR is a dead rpg, even though it is a great one.
Vires Animi