It almost sounds like he's saying בנוער -- definitely not hearing a שורוק at the end.
Since "us" is definitive it is banu. "He supports an us". Would sound weird in english
"Tomeyakh" would be the pronunciation if there were a ח on the end. The ך either says "-ekh" (f.s.) or "-kha" (m.s.) as in שלומךְ and שלומךָ.
בָּנוּ , without the nikud it's spelt just like His son, they really should use nikud!
No, they should not.
The man supports us. = .הגבר תומך בנו
The man supports his son. = .הגבר תומך בבנו (or .הגבר תומך בבן שלו)
Check out the web version and give the lesson a read. Its very helpful and will totally save yoy from being lost in this lesson.