Can I show up at the museum with my kids and buy tickets there for that day?

Yes.

Yes, arrive early. Check hours of operation on line.

Yup. Fyi, first Tuesday of the month is free admission for all.

Yea you can but there is usually a line so get there early!

Yes you can. Try to get there early to avoid the rush.

Yes, there's usually a bit of a line for that, but you can buy tickets on site the day of.