(Finally found how to answer)
Answer 1: My card is an ATI Radeon 3100 256 MB, probably a bit weak for SL, but it worked well until this particular viewer started gobbling my RAM. The antivirus solution didn't do much and frankly, I'd rather not "protect" parts of my HD unless Norton says it's fine, and they don't. Kudos though!
Answer 2: Lots of stuff, thank you. #3: I raised my bandwidth to 1,000. Can't hurt I guess, my connection is currently 8.45 MBps download, 1.04 MBps upload (that answers #8). #5: apparently no crash log, so I guess it's on my side that things happen. #6: I set my graphics to lower, OK I guess. Later I'll try to add a bit distance though, 64 meters is sad. #7: I get all my updates installed automatically. #9: I did that two days ago.
So I'll see what happens now (SL is already using around 480 MB) and report again if needed. Kudos to you too!