Personally, I would be wary of using any contract written by someone who isn't a lawyer. Telling people that you feel "there is no need to state the obvious as many contracts do" doesn't instil a lot of confidence either: how do you know what needs to be explicitly stated and what doesn't?
Getting a contract like this worked over by a lawyer would be a great help. That's why I open-sourced it, hoping to get more exposure and some feedback from knowledgeable people.
You might want to retain copyright until the work is paid for in full.
You can't really "issue" a contract. See http://en.wikipedia.org/wiki/Meeting_of_the_minds. This messes up your definition of "Developer". Just state the two parties by name.
The copyright assignment makes no sense. It basically reads "the client has copyright, except when he doesn't".
Termination: so I give you 14 days notice within the 30 day payment window and then all your outstanding invoices are cancelled so I never have to pay? Great!
I don't think you should have to get a lawyer, but you do need a contract to be unambiguous. I don't think that yours is.
