So, in order:
Teddy might not be the most sensible for Tobias, if only because he would rather not talk about it. If they were friends, though, perhaps it could be brought up without Tobias getting angry.
If you can think of a reason for him and Jack to meet up, that sounds great. Same for Claire. Especially since he's been promoted and works with her and all. In the Ministry maybe? Might be the day of his promotion or something?
Dom would be funny, but I'm not sure why she would interact with him, either.
As for yours, Hit -
Ryo makes more sense, considering Tobias is older. He's 24, so he would've been quite a bit older. And it would be interesting if Ryo and Tobias got to bond over children, but then Tobias lost his.
If Rose had a thing for him, it would be interesting, but he definitely wouldn't like her back. At least not right now. As for Yumi, maybe they hang out and things. Buddies maybe? Could've grown up together to an extent and she could have known his wife. Especially if she and Tobias got along really well. No threats for his wife, either, since she likes women xD But yeah. Maybe?