#1 sounds like “Escape 2000”, memorable for the squads of police rolling through town with “LEAVE THE BRONX” blaring from loudspeakers. And yes, there were a LOT of basement/sewer scenes (movie code for, “we were too cheap to build a lot of above-ground sets”).
#2 sounds like it might be “The Incredibly Strange Creatures Who <etc etc>”. There was a sketchy fortune-teller in the movie and the sound quality was terrible, so that might account for not being able to understand whay they were saying. I think the only really audible thing the fortune-teller says is “YOU FEELTHY PEEG!”
I’m not sure No. 2 sounds right. The woman I’m talking about reminded me somewhat of Diana from the original V but she talked like her mouth was full of marbles.
Try YouTube. Every episode I’ve tried to look up has been posted by some fan or another, albeit in 9 or 10 ten-minute chunks. It helps to know the exact episode number if you plan on searching for it this way.
…just did a quick search for “mst3k robot holocaust” on YouTube, and it’s up! Good luck!
Here’s a list of MST3K episodes that have been released to video officially:
For everything else I’ve bought a few DVDs online made by fans who were in the old tape-trading circles (they tend to just sell episodes that haven’t been officially released yet), and most of them have been good, but of course the quality of those is going to depend on the quality of the original fan recording.
There are a few episodes available for streaming via Netflix if you want good video quality, but all of these are episodes that are already available for purchase.