1. Only one instance of Runtime can run on each logged-in instance of Windows. Runtime can only run one deployment package at a time. In the deployment package, you can code it o do multiple things however. The RPA console will only send work one piece at a time. Until the bot has completed a work item, it will not get another one.
2. Workbasket and solution is the way to think of the relationship even though the workbasket is assigned at the project level. When you create a deployment package, you are creating it from the solution and it would include all projects.