For music playing at 7pm, are there usually seats available? We're coming to the restaurant--do I need to purchase tickets?

No you do not pay for tickets but they charge $5 to get in. You can usually find seats and if there are none available then just wait a few minutes and the wait isn't too long

Friday/Saturdays will be packed, but you can generally find a seat the rest of the week

I'm unsure. Apologies. The music there is great folk music though and sometimes top 40. I have not been to a concert there since Halloween and I did not have to pay in advance.