I've seen several other students at my DZ have the same problems. I've always had a good arch, but I definately get the blurry sensory overload. (my first PRP I totally forgot to pull, and first freefall, I spasmed and opened in a slighty poor body position.)
I think the key to success I've had is to RELAX. Fast is slow, and slow is fast. Another trick that's helped me so far in my progression is, while hanging on the prop, doing a last run through of what you need to do.
As for a good arch, I think the head position is pretty important; today was the first time I've screwed up my arch. I was doing my delta jump, and was thinking about that so much that the second I let go, I flipped upside down. Re-arched, and flipped right ways and got my jump done. My instructor said that my head was down when I let go, and that's why I flipped...keep lookin at that plane. :)
Anyway, just my newbie advice - sure there's better stuff out there.
Keep tryin!! The longer freefalls are comin' up, and they're worth sticking around for!
-Alex