Where to find documents/information about research group policies
You may want to check out this thread by @samuelmehr on Twitter:

https://twitter.com/samuelmehr/status/1139733291899080705

It gives an overview of typical content in what he calls a "lab handbook" (despite the different terminology, this is about the type of document you are looking for), plus a list of links to such handbooks which he reviewed to compile this overview.