"The innermost position will allow more chassis roll than outermost position. More chassis roll means more grip but slower weight transfer in a S-turn. That's my guess."
That is the response I got when I asked the same question. I just moved my links to the furthest position a few days ago. I'll be giving it a try next week at the track.
For #2, this is from the Tamiya site.
"The in-line position is suitable for slow speed technical track layouts whereas the off-set trailing position is best for high speed circuits. The trailing position also exhibits less responsiveness to steering input, which can be better if you're looking for an easier car to maneuver."