There is a private room. I think that it is okay to reserve a private room in the shop in advance.

Lunch is a set of 4,000 yen a little and put a drink and it is about 5,000 yen

Yes

Always the cheapest one you can leave (lol) 8000 yen There are three kinds of prices that you can choose.

No. According to the 2018 and 2019 Michelin guide there is no star awarded to Kyubey. https://guide.michelin.co.jp

How is a bar? I recommend"BarMitsuishi". https://goo.gl/maps/m5ZbjAdZx7N2

Probably yes, if you dont mind risking some disapproving looks by the staff. They're somewhat snobbish.

Yes!

no dress code, but it may be goog for u not to be too casual. enjoy