Yes, the drag and drop questions are reset on revisiting them. How difficult? Some people find them hard, some not. The answer is about the same as that to the question "How long is a piece of string?".
I myself thought they were pretty easy, but then I had prepared so dang hard for this test that they were all relatively easy.
It actually took 30 secs or so of trying to drag and drop before my first one "stuck". I started to panic, but eventually one stuck, and a realized that the mouse icon changes when you are in the right place to drop the item.
I didn't know they'd be reset when you revisit them, and so after I ran through the test once, I never revisited them.
I wasn't prepared for how very many there were. Must have been a good 25-30% of the exam.
They all look scary, but once you start looking at the code, and dropping things the first couple of things into place, the rest of the question falls into place.
Slideshow boring ... losing consciousness ... just gonna take a quick nap on this tiny ad ...