1. It would be better to have more context (as usual). This sentence can be neutral, not rendering any emotions, but it can also be "emotional'. In the first case, you may talk like this about a colleague who you know you'll meet because you work together. (You can say "Мы увидимся с ним tomorrow and I can ask him about that matter.") In the second, "emotional" meaning, you can use this sentence when talking about someone you're willing to see because you are attached to them or because you haven't seen someone you used to be attached to for a long time (and this someone is attached to you as well). It would be like "I am looking forward to seeing him - ("Наконец-то мы с ним увидимся"). Sentence 3 can aso be used like this, with a little difference - it would mean that you miss the person and he probably doesn't. 2 and 3 have been explained well here.