As I mentioned in some other post, you shouldn't blindly trust any plugin that modifies core tables. It's even worse if the modification happens by a raw SQL query.
1) Yes, it should
2) That is something that the core handles. It seems it should be OK for it to have those records in the ^userevents and the ^sharedevents tables. Anyway, after taking a closer look at how the core handles post deletions with regards to those tables, I conclude that the user one would eventually be deleted while the shared one won't. I guess there should be some cleanup in the core for the shared event too regarding deleted posts. Anyway, this is not serious at all.
As a side note, I created a new release of that plugin that considerably improves post movement. I basically threw away all NoahY did there and rewrote it from scratch. Give it a try and let me know if you find any issue.