Workflow template for multiple users && how to end a workflow

In my imagination, workflow template should be a “template” that different users could launch workflow instances basing on it, so that each user has his own workflow instance with his instance id, username, transition fields, etc. But in my test, after I launched a workflow instance with user A, then user B could not launch the same workflow template like user A did, user B’s workflow instance is silently ignored, have I misunderstand something about the usage of it?

And what’s more, another problem I encountered is: I could not end the process of a workflow instance! When creating a workflow template, there is an initial checkbox for the initial state, but there ain’t not a completion checkbox for completion states, so after I transit to the last state of a workflow, the workflow still lies there in the item list, I don’t know how to terminate it.

I think these might be simple questions but I’ve been stucked for a some days, could anyone help me out please, or is there detailed documentation? thx in advance!