Point 3: there's room. Not sure what angle can be achieved but I think with the right design enough. It isn't easy to see but look carefully here and you can see the db02 is angled. It has also pushed the steering rods into a much more 511 position:
http://kentech.blogs.se/2012/01/26/m...ures-12529054/
Bad news is I cannot think of an easy way of achieving this on a 502, you need a 511 style steering base I think to create the angle off a carbon chassis, if the db02 has the angle though maybe the next TRF will again.
From Lee Martins setups from Euro's looks like he was getting around the outer wheel lock issue by cutting into the castor block to allow more inner lock.
Re double slipper: I love it! It creates a system where the rear belt can slip Independant of the front belt, and I think this really helps it when landing off jumps on high grip tracks. Unfortunately, you can't set it independantly, you only have one nut, but it will slip independantly.
Doesn't Kyosho have something on their 4wd?