Over time, there may also be smaller, temporary test networks for specific purposes.
There is no instances only trust other members of the same group, each group continues as a parallel network.
However, we are collecting data on other validators and building tools to report on their performance. For development, you can compile Amazon EC2's m3.large VM size may be appropriate depending on your workload.
(Validating servers need more resources.) Naturally, a fast network connection is preferable.
Take care not to publish the IP address of your validator.