Would like to have replies urgently,as i'm in the process of evaluating several workflow engines.So that i can use them in my project
1: the name says it all. It is the class that implements the functionality so you can specify in the process what should happen when an error occurs.
2: Depends on what you configure and on unknown bugs (known bugs are in jira, you have to look for them yourself)
3, part 1: no idea, think it depends on how you implement the errorhandlers
3, part 2: if you want specific behaviour, implement errorhandlers