Do we support a 3-node cluster spread across three AWS Availability Zones?
This is a normal deployment pattern for working in AWS reduce risk. A single cluster works quite well in this topology.
What are the best settings for the Tungsten connector intelligent proxy?
Standard settings work out of the box. Fine tuning can be done by working with the specific customer application during a Proof-Of-Concept or Production roll-out.
How do we use Tungsten to scale DB nodes up/down?
Currently a manual process. New puppet modules to aid this process are being developed, and will be included in the documentation when completed. Here is a link to the relevant procedure Section 3.5.1, “Adding Datasources to an Existing Deployment”.
Do you handle bandwidth/traffic management to the DB servers?
This is not something currently supported.