You can test non-packaged standalone by navigating to your ue4project.exe file, right-clicking, play.
Testing for Vive can be a pain-in-the-■■■. It seems half the time it will just work, the other half you have to make sure that the headset and both controllers are awake and visible by the sensors, akwardly holding all devices up with one hand, launching the project with the other hand. Will still sometimes not work. Oh, also make sure steam and steam vr are running.
No such trouble with oculus, except forgetting to tick “launch in vr”.