Is this suitable for a toddler?

Yes

I would say Depends on the Child

The entire cruise in only 40 minutes so won't be an issue. Certainly I would recommend an afternoon cruise for a toddler. The top floor is open to sunlight but the bottom two floors are covered. Also there is a kids menu.

I don't think so either.

I would lean towards no, but it's probably ok.

I did a night cruise and it was fantastic. As for having a there toddler would better in the noon cruise. Less crowded.