New Fiesta owner - few questions

[razredge]

Hey guys, so about two weeks ago I bought a 3 door 2009 WS Fiesta CL with about 30K on the clock. So far I really like the car, looks stunning and drives very well but I have a few questions.

It's only a 1.4L auto (I can't drive manual, considered buying a manual WS and learning, but thought better of it - since the car is relatively expensive and I live in a very hilly suburb) so it's not exactly fast - though apparently it's about as quick as the old WP/WQ 1.6L Autos?
With my uni student budget I was originally looking at the WP/WQs but decided to pay the 2/3 grand extra and get a WS - which I think was a good choice.

Anyway I managed to find the 5 spoke manufacturer 17" wheels for cheap and got those fitted this week with 205/40 Kumho KU31s (which were also cheap and not a bad tyre apparently).

However, Ford specifies that when the 17" wheels are fitted a steering rack limiter is required (as well as ESP) to comply with ADRs or something.
Now to me it seems a bit unnecessary as the wheels are only 2 cm larger in diameter than the 15"s I upgraded from and I did a few low speed manouevers with steering at max lock and didn't hear any scrubbing.

Has anyone else fitted 17" (or larger) wheels to their Fiesta (without rack limiters) and had any problems with the tyres scrubbing the bodywork?

The other thing I was interested in is the difference in suspension tune between the WS and the WTs? Were the WTs softer to better suit the Asian market?

Also, apparently all WS models from CL to Zetec all shared the same suspension tune but with the WT the Zetec got a sportier setup (lowered & stiffened I presume). However on the current Ford AU website there doesn't seem to be any mention of a different suspension setup for the Zetec?

And should I be using 95 or 98 octane petrol, I don't think they're any benefits to running on 98 since the 1.4 isn't that sophisticated (compared to the 1.6) but have any 1.4 auto owners noticed a difference between the two?