Quick answer:
Yes, you will lose (not loose!) your H-1B status, but no, you don't have to move automatically to EAD. It goes like this: If your H-1B papers are still valid, and you work for the same H-1B sponsor when you come back as a parolee, you can work for your H-1B sponsor for the duration of your H-1B validity without an EAD even though you are not in H-1B status. If you file an extension of your H-1B documents later on, that will reinstate your H-1B status once approved.
So basically you will be a parolee (not H-1B) but are allowed to legally work by virtue of your current H-1B documents. If you go anywhere else or take a second job, then you'll need to use your EAD.
