1- 'Tom's over' is possible- if Tim's visiting my house and someone rings me I could use it to say he was visiting. It can't be used to mean the same as 'Tim's up', which means he's out of bed.
2- It doesn't sound right to me. It should be 'you did' or, possibly, 'you did see', but 'did saw' doesn't work. Which character was it? It could be a deliberate mistake to suggest that the character did was not a native speaker.