Hey Phil, thanks for the awesome questions.
1. Though I didn't come from Windows Mobile, I can talk a bit about what attracted me to Android. For me, it was a choice without choice. Living overseas, there are many phones to choose from, but a surprisingly low number of smart phones available. The carrier that supplied the iPhone flat out refused to sell me one unless I paid the full price up front (with the exchange rate, it was roughly 800US$, plus it was locked). Windows Mobile phones are on a carrier that's viewed as a joke. My Android phone (the HTC Sapphire) filled all my needs: versatility, size, price and potential. Having installed about 14 different flavors of OS, I find it's the perfect fit for anyone who likes to see something new every so often.
2. Not at all. There are some features I see and say "Damn! That would be awesome!" such as the keyboard that the Verizon Droid has, or the horsepower of the Nexus One. Overall, though, the constant evolution of the phones and software means that Android has a very big future ahead. As silly as it sounds, every new phone makes me salivate thinking what might be in store whenever it is finally time for me to upgrade (either due to a broken phone or lottery winnings). Google seems to care about where its smartphone market is going, and as long as I can get support for my current phone and keep looking towards the future, I'm content.
3. Stock just doesn't keep me interested. Viva variety! In addition, having not bricked my phone yet keeps me positive about the flashing experience, so that helps.
4. Constantly. However, there are really only three ways to deal with Google's megalomania. Either I can try and live off the web (as Google seems to have a hand in almost everything internet related), I can work my hardest to use alternative web resources (Bing, Yahoo, etc.) or I can relax and be a part of the winning team. Call me a sellout, but Google hasn't busted me yet for sending emails to [REDACTED] or using their search engine for finding plans on [REDACTED], and after that, everything pales in comparison. So yes, freaked out, but trying hard not to care.
5. MobileMe support. C'mon guys, I paid for this thing to be Mobile, please don't make me log into a computer everytime I need to check email.
Hope this helps! Happy hunting!