do we have to be in our seats at a particular time? I may be getting to the venue a bit late. Thank you

no

I was late. I arrived when the main act just started and they let me in without an issue

Nope

no you can be late

No, many people come in late

No you don't, it may be better if you can get there on time or a little before, but it's not a must

No, a lot of people came in after the main act started.