yehp 17x8jj rims required

what you said about the stretching of tyres over the rim is true, as it pulls on the sidewalls so that they are already tight and wont flop... this being said too tight and the tytres can be pulled off from cornering or hitting a kurb.
a 255 is gonna flop.
a 245 less so but too expensive with a 245 tyre so 235 is ya best bet, should be more affordable to get one with a good sidewall construction.

on a FWD car you will need more rear camber than front to help with handling, all manufacturers recognise this and many cars that even dont have rear adjustable camber will come with about 30' (0.5 degree).

Camber on the front wheels is good for applying power through corners and minimising understeer. however your front wheels wear fastest since they do most of the braking and all of the steering/power transfer.
the more camber you have the faster they will wear out and in a straight line you will have less contact path to apply brakes and power.
you need to find where you are happy.

now for offsets you will most likely be nabbed if your wheels are poking out, for inspection just swap the rims over.
my s2k recommended something like +55 offset or something which where the stock rims but my new 17x8s have 45 and they just fit (maybe stick out by 2mm) i would imagine that you should be fine with those spec, but keep in mind you will not be able to rotate the wheels. basically keep the +43s at the rear and +45s at the front.

adjust front camber to 0.5degree (ie 30' minutes)
if they do stick out a lil.

measure the distance from rim edge to fender.
then using your current rim specs enter the data into here
http://www.jdmconcept.com.au/wheel-offset-calculator