1. It can be silent or extremely loud. It all depends on how much airflow you need to dissipate the heat from the coolant. For example, if you have a couple of graphics cards on a 120 radiator, you will need a hell of a fan to cool them sufficiently. However, if you put it all on a 480 radiator, you will hardly need any airflow. Most pumps are very quiet.
2. Case fans are still required. Many things that are not on water blocks such as NB, SB, RAM, HDDs, etc. still need airflow.
3. You can nearly always get better performance from a custom system. It is also much more flexible, obviously.
4. What components do you want to cool?
5. Leaks are definitely a concern. However, a properly assembled loop is very reliable. You won't have to add fluid as it is a closed system. Occasional maintenance includes draining fluid and replacing it periodically. Unless something is wrong (never cleaned the components before assembly, allowed algae to grow, etc), that's all you need to do.
2. Case fans are still required. Many things that are not on water blocks such as NB, SB, RAM, HDDs, etc. still need airflow.
3. You can nearly always get better performance from a custom system. It is also much more flexible, obviously.
4. What components do you want to cool?
5. Leaks are definitely a concern. However, a properly assembled loop is very reliable. You won't have to add fluid as it is a closed system. Occasional maintenance includes draining fluid and replacing it periodically. Unless something is wrong (never cleaned the components before assembly, allowed algae to grow, etc), that's all you need to do.
