Some nice 17's look the biz yes, you;ll need 45 profile tyres to keep the
rolling radius right, otherwise they just bolt on. Personnally I think the
MP3 alloys look the part.

Yes the HU will fit- just pick up the dash adapter. The online sellers ones
do a silver one to match your dash. You can fit the HU either in the top of
the hole or the bottom, I prefer the bottom as you can get a more solid
mount.

Why do you want your 6x9's on the back shelf? Do you drive from the back
seat? No. As long as their not too deep, 6x9's will go straight into the
front doors to replace the factory 5x7's. If the magnet does foul the window
winder you'll need to make up some mdf spacers to push them forward alittle.

Get some decent power to these speakers (external amp, ~75w RMS) and run the
factory rears from the HU internal amp, balance it out with the fader about
80% power to the front, 20% to the rear and you'll have something that sound
200% better than standard for very little work. The next stage from there
would be a sub in the boot, so if you dont have a decent amp, and you may
want a sub in the furture, think about buying a 4 channel-er. (can bridge
the 2 spare channels to 1 to drive the sub when you get it)

Tim..