Most of your questions about Broadleaf versioning for the inventory module are answered in this post: viewtopic.php?f=15&t=1835&p=5091#p5082
So yes, Broadleaf 2.2.1-SNAPSHOT is a minimum requirement, while Broadleaf 2.3.0-SNAPSHOT is recommended.
However, that being said, we have been working on Broadleaf 3.0 which is a very large release and removes all of our GWT code from the admin. We went and rewrote all of our admin code to instead use Spring MVC. We are currently recommending that clients that are starting new implementations use the 3.0.0-BETA2 version of Broadleaf (which is referenced by the BroadleafCommerce-3.0.0-BETA2 tag in the main BroadleafCommerce Github repository as well as the DemoSite repository). That being said, we have not brought our modules (including inventory) up to date with 3.0. This should happen over the next few weeks.
To your other points, we do have a compatibility chart for our modules located at http://docs.broadleafcommerce.org/curre ... ility.html
, but it looks like we do not have information on the inventory module. I will ensure that gets addressed in the next couple of days.
Thanks for working with us, and sorry if this has been a little frustrating so far. Let us know what else we can do to help!