Sayuri-Ryuu
Possibly, but they could have made others that were destroyed or lost or - heres a thought - taken over by the Wraith that were never mentioned on earth.
most likely not because then they could have made new warp technology to get to earth a long time ago because they would have found out about it because they ran away
my real question that i just thought of is why did the wraith give up on the siege of atlantis after it was abanded if they looked for it they would have found it in no time on that planet.