Thanks for using Alces Flight! Please could you let me know which product, and which version, you're currently using, so I can be sure to answer appropriately?
The autoscaler checks for demand every five minutes, which is why you're seeing a slight delay in compute nodes being generated. This is not currently configurable, but (as your next question demonstrates) it's possible to start up the cluster with a number of compute nodes ready to go.
A compute group started with one or more initial compute nodes will always keep at least one node running, but it will terminate any additional nodes if there is insufficient demand. There is not currently a way to maintain a minimum number of more than one node without disabling autoscaling (by running
alces configure autoscaling disable).
It's not possible to launch nodes of differing types within a compute group.
AWS does not support scaling across multiple regions, I'm afraid. It may be possible to request an increased spot instance limit for your account from AWS.