Choice here too - have been running Linux at home for almost 10 years and I never regretted it. There are almost no downsides, except careful choosing what hardware to buy and the lack of Photoshop (though Wine helps with that now).
Touch scrolling is not enabled for mobile devices since there is native scrolling already (with two fingers in iOS below 5 and with one in iOS5). Custom scrolling can be additionally enabled.
Regarding the license - we are using a "beta" license that should protect people from using beta quality software in production. We'll move to the dual-licensing scheme once we are out of beta. We also updated the FAQ accordingly.
It can be seen as flicker in Windows and there are some reports of black flashes in OS X. Switching the 3D acceleration off seems to fix them, but unfortunately it can be done only with a command line switch. We may forfeit the CSS transition animations in Chrome in later releases if we can't find a fix for these issues.
Well, Apple's repos and bugtrackers are internal so we may never know. However the differences between them can indicate separate repos or at least far away branches. N9's browser is built from WebKit2, so it may be also more prone to crashes due to Chrome-like process separation, a feature Lion and iOS 5 will also have.