The ship in question is similar in design to a Vulcan ship...it's actually XCV-330
SS Enterprise.
Kirk actually states that all these ships were named Enterprise...
As for the Borg, Archer refers to Cochrane's warning of "cybernetic aliens" and we hear the aliens announce the "Resistance is futile, you will be assimilated", but I don't recall anyone saying "Borg".
As far as Q goes...that is easily understood...Q warned humanity about the Borg, even Picard says so.

Q does similar, seeming nasty things on several occasions...and they turn out to be beneficial. Take a look at the TNG finale
"And All Good Things", Q warns of the destruction of the galaxy, and points Picard to the solution.
Let's face it...with the exception of the "sublight Romulan War" the writers of Enterprise can "star trek" an explanation for almost all the other variances.
