Don’t use *GetAllActorsOfClass *node for something like this - it’s meant for something else and this just leads to bad practices. What if you have 3 actors - how would you know which of the 3 the node fetches is the one you want… ? It does not even guarantee element order 
How actors communicate will depend on what you expect to happen and how you set things up. Actors in the level blueprint vs actors spawned run-time, for example. One widget per actor, or one widget for many actors, many widgets that manipulate 1 actor, perhaps? Are you going to work with inheritance a lot? Do you need *unrelated *classes to talk to one another?
Just posted this, see if it answers your question:
https://answers.unrealengine.com/que…ed-distan.html
This is a self-contained method but dispatchers can be hooked up to anything. More here.
Edit: check here, too