in my case I had reserved (the day before) the tickets for a time slot BEFORE 5pm but eventually the etickets reported 11am-5pm as validity. I wanted to go there at 15 but apparently any time would have been fine between 11am and 5pm. But yes, maybe if there are car races they might be stricter with the time slots. And about being late or early, it will also depend HOW late/early you're going to be; surely 10 minutes won't be a problem. Just make sure you are around the Skypark and not on the other side of the Marina.

There was no time limit as to how long you can stay. We saw people that had been there most all evening and some were in line to leave right after coming up. Take your time and enjoy the view!

I think you are asking does it need booked in advance, like a lot of things in Singapore you do need to buy the tickets electronically to get a bar code. We did book the tickets onthe day though, seem to remember you booked for a time range which might have been more to do with COVID regulations, they do shut for lightning as well for safety reasons

I believe the Gardens are a fair little walk from the hotel I seem to remember walking across bridges. We did it at night, very pretty walk.

When you get to the Marina Bay Sands Hotel, there is a ticket office and machines for you to collect or purchase tickets. Once purchased you get into the lifts and go up 56 floors to the observation deck/57 doors to the restaurant/bar. Fantastic experience

There’s is a cost which includes a drink. The bar name is very c’est La Vie

Hotel guests only. You can go up and eat drink at the sky bar without paying a fee, rather than buying tickets for the skypark.

If you are not staying at the Hotel, there is a visitor entrance at the back of tower 3

I think no..

check your tickets otherwise I do not think there is any problem