Where can I watch old Cartoon Network cartoons nowadays?

On streaming platforms such as Netflix, Max and Prime Video.

Are there any remakes or continuations of these cartoons?

Some of them have had remakes, such as The Young Titans, which got a "lighter" version known as "The Young Titans in Action", and The Powerpuff Girls.

What are the most acclaimed Cartoon Network cartoons of the 2000s?

All the titles on this list, especially Courage the Cowardly Dog, The Powerpuff Girls and The Young Titans.

The 11 Oldest Cartoon Network Cartoons, Ranked!