Some basic questions about Genosis
Genosis
Think of a "researcher" as like a profile admin - they can update all Genosis profiles - just like a regular JR admin. A contributor is just someone that "owns" a profile.
As for surnames - yes - you can "build off" as many profiles as you want. For example - you could set the home profile for one of your relatives in the tree as their profile, then they can "add" parents, siblings, etc (as long as they are a researcher). That's how I run things on my family tree site - for example my sister has a profile and can add relatives as needed. The map that is part of Genosis right now is just based on birth dates - not names (and with Google getting rid of some of their map stuff it may not make it for long).
Genosis is super flexible - I'd recommend getting in and playing around with it - you'll find there are lots of shortcuts to make things easy.
Let me know if that helps.
Thanks!