Personally, I would postpone learning about fork and lower level socket programming. They are necessary to learn about but you better learn about them once you have a situation that requires you to instead of learning about them now and never getting to something that produces results.

I would avoid POE and IO::Async for the same reason - unless you have a situation that requires you to use a state machine or callback based approach for concurrency, knowing about them serves little purpose.

If you want to write servers or middleware for SOA (which I presume includes the buzzwords REST or Microservice, nowadays), I would look at Dancer or Mojolicious for getting a quick start. They both can act as stand-alone servers but can both leverage Plack/PSGI to use other webservers. If your application ever outgrows what these frameworks provide, Catalyst gives you an environment that needs far more up-front setup but supposedly provides much more structure. Personally, my applications never reached the complexity that might warrant using Catalyst.

I believe that most (if not all) of the Dancer developers are now working on Dancer2. Also, it looks like http://perldancer.org/ is starting to reference Dancer2 instead of Dancer in it's documentation. Considering all of that, would it be better to recommend new folks to look into (or use) Dancer2 instead of Dancer at this point?

In my opinion, Dancer2 is very much still under development, so I don't consider it as good for a learning experience. But depending on how adventurous Divan is, Dancer2 might still be an option.