Stress? Rule changes make it fun for them... these people should be at there best when challenged.
Yes, then the 2008 engine freeze will mean they will never be challenged again afterwards when it comes to the engine.
They are allowed to work on the reliability, but still, secretly they all care about performance... probably
The design proposed by the FIA works quite properly.
I'm not too fussed about anything but the engine freeze, but I can't honestly imagine that split rear wing thingy producing useful amounts of downforce. There'll be massive amounts of turbulent air coming off the (now wider and slick) rear tyres, surely interrupting any air flow below the wing.