how common is しばらく I was watching ドラマ Dr. JIN and heard someone say ”しばらくだな” I was curious if it was an older way of saying ”おひさしぶり” because the main character was sent back in time in the episode. Is ”しばらく” commonly used today in Japan?

how is "あっちゃ” used?/exact meaning I was watching a Japanese TV show where they were eating hot (spicy) foods and one person said "あっちゃ！あっちゃだわ！”