Den, it will depend upon whether you are using "means", as singular or plural. If they are multiple means, you'll use the linking verbs "were" and "are". The structure of your three examples are more comfortably-spoken in plural form. Perhaps someone else can improve upon my response.

1. The means they provided us with were good.(I think this can be singular or plural depending on what you're talking about.The "means" could be one thing - a particular way of eliminating trash e.g. more trash cans, or many "means"- trash cans, clean up crews, recycling programs etc.) 2. The means of support they provided us with was good. 3. The means is not sufficient for the end.