I would really like to see that experiment. A basketball rotating for 24 hours, one revolution, with 70% water to start. You're thinking the water would hug the ball? How would you scale back the gravity?
The ball would need enough mass to effectively attract the water molecules, and it would need to be far enough away from other bodies (the earth) so as to not be affected by their gravity.
Yes, the gravity needs to be scaled "back" with the size of the ball. Basically if you scaled the earth down, all atoms would scale down with it, increasing the density of the earth and of the water its gravity attracts.
If the earth really were a ball with its own gravitational pull, floating in space where external gravitational forces are for most intents and purposes negligible regarding things close to the earth, there would be no way for the water to just fall off, because there is no significant gravity pulling from wherever you decide "below" is.
The problem with the basketball experiment is that there is the earth, a giant powerful source of gravity, pulling the water off the basketball. It would be like trying to play with magnets next to one giant magnet such that nothing ever stays in place.
For the best chance of success, I'd recommend putting a powerful magnet inside the ball, and letting it attract ferrofluid, which would spread out over the ball. This would simulate gravity.
Round can also apply to a flat circle, so I'll assume you mean spherical.
When the sky is observed through a ground telescope, as the following video
All you can say with certainty about the observation is that a circular light source was observed. You can't infer a spherical shape for certain without another point of view.
Take the attached image as my point: Is it a hollow inverted pyramid, a regular pyramid with the peak towards the screen, or a 2D square with a cross in it? You wouldn't know unless you observed it from a substantially different point of view, and no one on Earth has shown that for the alleged "planets" (they are just stars)
Well, if you make enough observations throughout the night and day over enough days, you will see that the sun rotates like a spinning globe, so does jupiter, and you will see the moons of jupiter orbiting around it. The fact that you can see something on the sun or a planet rotate to the far side and reappear again as it rotates back into view, suggests they are globes. It may even be possible to detect the change in size of jupiter's moons as they get closer and further.