I'm a badass and I still have McD's soft serve. I figure it must turnover pretty quickly, so there isn't that much chance of it going blurgh in the freezer.
I wont eat from a soft serve van though - no way known!
Ham is fine cooked - so as long as your sandwiches are nice and hot the listeria should be killed.
Just be careful - it only takes one dodgy bit of food to make it all happen, so while its easy to say your chance is low, its still best not to take too many risks.
I actually had an raw oyster last week..... But I know it was freshly shucked that morning, so I wasn't tooooo stressed about it.