I just gave them copy of online statements of my bank account in US. They had my name, account number. I guess, they are looking for that.
They are particular about job duties and work duration including hours. In my case, all of my experience letter had work hours.
I think, they want to make sure someone doesn't claim part time work as full time and exact job duties for NOC match.
Don't request WES as yet, wait until they actually ask you to do so.
When in doubt, look at the application guide. It is has all details. I didn't even read it and was in a hurry to submit all documents.
I would have saved some had i read the guide before registering on their web site.