I totally gasped when I read your post.
Maybe your new EHD is a dud? I think if I was struggling with all that I would either upload everything to an online storage place (crash pad is offering 20% off right now so it would be $40 for the year, they might even give you a free trial) or put it back on your HD while you figure it out, or return the EHD for a different one.
I am looking at getting a second back up EHD so I will have two. I have had great luck with the EHD I got from Apple (it's a rugged- the one with the orange rubber around it), my kids dropped it down a flight of stairs. I need military grade stuff, since I have toddlers LOL. I have heard that people around here like My Passport, I was considering one of those too. I have nothing but good things to say about my rugged though.