Actually isn't that an R5 unit? (seen in ANH a couple of times, though one of them was replaced in the SE by a dinosaur IIRC).
I guess I'm not a big enough SW geek to know.
I don't recall where the tall "health droid" is from. I remember there being a toy of him, but I don't remember what part of the movies it was in.
The boxy Gonk power droid of course is seen several times. In ANH it's on the Sandcrawler with R2 and C3PO and you see one being tortured (hot irons on the feet) in Jabba's Palace in ROTJ.