On UR Support Site you can find release notes under FAQ and the URSim under Downloads.
If you sign up for notifications (bottom left) on the support site, you will receive an email, when new SW is released.
When new software is released, it will also be published here.
There is no difference in the SDK from SW 3.3.0 and 3.3.1, and the minor changes from bugfix 0 to 1 is described under the 3.3 release notes under FAQ.
Bugs are reported from Distributors to Regional Technical Support, and bugs related to URCaps API and SDK is reported to support.urcaps@universal-robots.com or in here.
You can have multiple URSim’s installed in same Linux VM.
You just have to modify the path of deployment for your URCap project and navigate into either folder to run start-ursim.sh