Hey AnyRaiN-
There are a few questions I have that will help me investigate the crash errors you are reporting.
Do any of the reported crashes occur when you only have the BP_BaseCharacter and not using the sub-classes?
Does the crash happen if you use “Cast” nodes rather than an interface for the BP_BaseCharacter?
Does the crash occur in a new empty project with the created class and sub-classes?
Do you still get the crash on the latest 4.7 preview 5?