Absolutely to all of the above. A developer's job is to determine what's actually wanted/needed, not what is exactly enumerated, especially in a startup. In a

Absolutely to all of the above. A developer's job is to determine what's actually wanted/needed, not what is exactly enumerated, especially in a startup. In addition, if a job needs done, a job needs done. A developer who can hop on a sales call, or do customer support when needed is invaluable in an startup environment.