Karaoke etiquette? How do we behave correctly?

Hi everyone!
Soon I'll be back in Japan (hype!) and want to enjoy karaoke with a friend while I'm there, but I'm curious about the proper etiquette in a few situations that I stumbled upon the first time last year.

1. When drinks are brought to the room but I'm in the middle of singing, what’s the polite way to handle it? This happened the last time I was there and then I awkwardly stopped singing but couldn't find a way to pause the song. Should I keep going, take a pause, or somehow signal for a break? How do I properly pause the music?
2. How do I recognize if a karaoke also has a 飲み放題? Just from the signs? And are the 飲み放題 in a Big Echo different from a カラオケ館? Any recommendations? 🙂
3. How do I politely ask for an extra hour at the karaoke place when they call? Is it okay to say "もう 1 時間 お願いします" or is there a better phrase?

Thanks so much in advance for your help!