Yes, absolutely. One fill is more than enough.
The water stream is strong enough and is comparable to a stationary bidet or water-jet.
No, it does not become dirty since it doesn't touch anything on your body. It is not intended for contact and is engineered to hit the right spot with very little splashing on the device. That said, it can be easily rinsed by running a little water through it and wiping it dry with tissue or a little alcohol swab.
No, you do not need to install anything.
It's not absolutely silent. People nearby will be able to hear it, but it's quiet enough that it's not generally disturbing.
Does it warm the water? Or do I have to wait by the sink for warm water and fill it up each time before I use it?
No, it doesn't warm the water but room temperature water is quite comfortable, even refreshing.
It is fine for carry-on use. You wouldn't want to fill it with water anyway when you travel. Keep it empty. If you need to use it on the plane, just fill it up in the plane's lavatory. It's easy and fast. The airport security restriction is for the liquid itself not bottles or devices that carry liquid.