1. yes. you can have 2 (or more) caches with different configurations within the same CacheManager. The cache mode is configured as Cache level, not at CacheManager level.
2. What do you mean by Infinispan instances? if it is CacheManager, then yes, you can have multiple cache managers running in the same JVM - we recommend one if it is possible as multiple cache managers would duplicate resources(e.g. jgroups channel handle). All the caches associated to an CacheManager share the same transport(jgrous channel), so if you need to be part of two different jgroups clusters you'll need two CacheManagers.