What event is triggered in Restart Workflow?

Hi

We need to execute some custom methods which updates custom table within workflow. But then when we will restart the workflow those custom method will execute again. So I was thinking of using SkipToStage functionality. To handle this I have few questions

1. Does SkipToStage variable has true value only when Workflow is restarted?

2. Can we put in SkipToStage ifelse statement before first stage of the workflow? (or it is always inbetween SetProjectStage?)

3. can we get SkipToStage values true/false and GUID into variable and use them in custom code?

4. Is there is any other event which gets triggered in Restart Workflow which I can use to write some code?

Please advise.

Thanks

Dipti Khandke