Yes, Anders Hejlsberg did various times in podcasts when they announced the move go. It has nothing to do with C# not being capable enough, but rather that a line-by-line port from Typescript to Go would be easier. I think IIRC several time that had LLMs be more advanced as they are today, that choice would have been a different one.

Yes, it's because the structure of the existing codebase for the typescript compiler matched go better. (There's a blogpost about it somewhere)

edit: I think it was considered, but go was a better fit