I’m not sure what would constitute an Erlang open-source community exactly (maybe it’s a sub-set of the following) but theres definitely an Erlang community - and I would say it’s made up of anyone who’s positively interested in Erlang and wants to interact with, support, and welcome others into it - and all in a sincere, kind and thoughtful way. Together, these people form the community 
People can also be users of something but they don’t have to be a part of ‘the community’ if they don’t want to be, but generally anyone who is a positive force and adds something of value can, and are usually welcomed with open arms too 
Obviously this is in the most simplest of terms but you get the idea 
Absolutely! I am hoping this forum can help, and I’m already enjoying seeing so many Erlangers come together and talk about community orientated things - just like you are in this thread, and others like this one and this one and this one and this one (and we’ve only been live something like 10 days!! 
).
I think the future of the Erlang community is looking bright - and it’s all thanks to fantastic people like you all pushing it forward 