I also don't see much of a similarity between the sleak, arrow-like E and the NX-01.
Nor do I. Aside from color, they don't look anything alike to me.
Both First Contact and Enterprise were released before ST09. The alternate-universe-time-travel thing was invented as a way to appease fans over the reboot (and I think it's obvious now that it's an outright reboot). It's silly to go and apply it to all time travel we've seen in Star Trek before, which was always traveling back and altering/restoring one timeline.