Sorry, I have no idea where they filmed Abydos, but I can see the Aussie resemblence now you mention it (I'd always thought it had been filmed in the desert in Africa somewhere )
And to the first question, the Movie is out on DVD here in the Uk, and I'd guess other countries too, but Stargate 2 hasn't been filmed yet, but once they wrap up S6 then I guess work will begin on it (getting all excited!! )
Well, it was either filmed in Egypt, but none of the scenery or buildings looked familiar for Egypt, or the pyramid was a shot of one at Giza put into the shot, or, the most likely, it was CGI or other special effect, a model for example...
I'm sure it was filmed in the US, I think the mojave desert in California. I just know that they had to erase dune buggy tracks every day before shooting. The pyramids in the beginning were old stock footage they updated and put in the CGI boat and everything else to make it look real. The pyramid on Abydos wasn't real, but the temple entrance was a real structure they built in the dessert. If you look closely as O'Neil and Jackson walk out for the first time, Daniel runs his hand across the supossed rock and pushes on it, the rock pushes in, he of course doesn't look surprised or anything but it cracks me up that no one caught that. Continuity errors are few but they stick out like sore thumbs after you've seen it as many times as I have. As for the spaceship landing on the pyramid, that was all minitaures. I think the special effects were done pretty well considering how much the movie cost. I missed alot of the errors my first few times watching it and only caught them after looking for every detail and not watching the action going on. Like I said though, it's done very well and with a surprising low budget.
The entrance to the Abydos city was obviously real and they just used CGI to expand it to the view of the whole city. Mostly studio parts were filmed in England in the hangar where that big plane of Howard Hughes's was kept. They needed a huge studio to build all their sets and couldn't find one big enough so they somehow found out about that hangar, and used it. They even lost several weeks of shooting because of an earthquake and lost some equipment and sets too. As far as I remember it was only filmed in the US and England. I just might have to watch it again and let you know if anything I said is wrong. But I doubt it, as I've practically memorized the stupid thing by now. Stargate Trivial Pursuit anyone????