Unfortunately it’s not currently possible to implement custom EQS tests in blueprint, sorry! If you’re willing to use promoted UE4 from github I would be able to bring it in in couple of days. Let me know.
No to worry, I got a copy of the Git repository to see the .cpp code for the tests. It seems that tests are fairly simple and are basically just implemented in the RunTest function.
Generally speaking, yes. One thing to remember though is that you should use FEnvQueryInstance::ItemIterator to iterate over items and set scores or test results.
I’m terribly sorry but this feature is currently on hold due to many things of higher priority happening now. It’s not forgotten though and will get done past-GDC-ish