Noting that I'm in central Tokyo, the only thing that sounds close to me is a super-dramatic やっっったー！ in the way of a celebratory analogue.
That said, you're looking for the 'agreement' meaning, as in:
Anyone down for karaoke? / Fuck yeah!
In that case, the example conversation playing out in my mind resolves to
カラオケ行く? / 行こー!
And in other cases...
飲む？ / 飲もー！
帰る？ / 帰ろー！ (as one might say when they want to get out of the office)
Other words of agreement like 是非 or もちろん or いいよ just don't have the adequate punch. The enthusiastic volitional -o-! is my best suggestion.
In the case of agreeing with an opinion, rather than a suggested action:
Trump is the Abe of the West / Fuck yeah! (maybe you're goddamn right would be a better English response here, but the sentiment remains)
トランプは欧米の安部 / それ！完全にそれ！
In this case, the enthusiasm and immediacy of the response capture the emotion more than the words.
As for the final possibility, satisfaction, I think Sjiveru's answer covers that quite well.