If you just wanna walk around is there still the admission fee?

Yes

Yes. You could enter through a ticket center only. And most of the museum is walking around and entering the places that are setup there. Some of the places like planetarium or boat building has extra tickets but there are a lot of other activities included in the price. The boating is very cheap too that you could do and go near the drawbridge and watch it open at 40 minutes past an hour.

Yes.. it's the same fee.

Yes. $28.95