From what I understand, if your business name is "ACME Sydney", then having the domain acmesydney.com with the location keyword in the URL is preferred, after all it is your business name.
However if your business name is "ACME Plumbing", I wouldn't purchase acmeplumbingsydney.com just for the sake of having a keyword rich domain name.
As for whether or not having multiple keywords in the domain is a good idea. I'd say no, if you're going to include a keyword, only include one and only if it makes sense to include it (i.e. it's your business name).