We use logback.

As of version 1.19.0, here is the logging pattern: <pattern>%d{"yyyy-MM-dd h:mm:ss.SSS a"} %-5level %logger{75} - %msg%n</pattern>

Older versions, prior to 1.19.0, use this pattern <pattern>%d{"MMM dd, yyyy h:mm:ss.SSS a"} %-5level %logger{75} - %msg%n</pattern>.

8GB is way plenty. 1 or 2GB is generally adequate, it can depend a bit, but FusionAuth doesn't keep much in RAM. Scaling out horizontallly is likely more effective than more ram per instance. This way you can handle more logins per second--these are going to be cpu bound.