most of the Goa'uld stuff is supposedly based on Ancient tech blended with their own sense of style.. the sarcophogus was based on the the ancient healing device from the ep "Evolution".. the fountain of youth thing. as for the rest, prob other ancient stuff, but we know there are plenty of other races in the stargate universe that have decent tech they prob pirated.
i quite like atlantis. sg1 has gone down hill lately most definately. quite glad there isnt gonna b a season 11. atlantis will carry on most of the stories nicely.
the films will probably be direct-to-dvd. they'll wrap up loose ends and tie up the Ori storyline. Prob end up with time travel somewhere in the story i expect.