Hello,
You might have too much RAM for Tetris. Some progs might need to test to see if there's enough RAM, but the test may assume there's max 64k, which would be the normal for the PCW. Actual available usually about 61k. So maybe 77k looks like 13k or something. If you can do that, try getting RAM down to below 64k first?
I'm pretty sure NOTHING can make the std PCW speak, it's got a crude beeper ONLY. You MIGHT be able to do something with something like the dktronics sound module, or the speech unit? Maybe attempts to communicate with something like that are causing the Gotek to flash?
Can't comment on the other two points.
Geoff - totally a Command Prompt person.