I'll answer question 1:
I'm in the pilot phase of a new web application on app engine. We've spent about a month writing code and getting things ready for our first customer. They went live last week. They love the software but a couple of days ago I started to get random deadline exceeded errors in the application. You look up a record or a list and it would come back in miliseconds. The next go it would take 30 seconds and come back with a deadline exceeded error.
The stack traces in the dashboard give random results. I've tried everything, even stripping the app down to a hello world. I put a log message into our django process request middleware, the first bit of our code that gets executed. It was showing that on the timeout requests it took 25 seconds from google getting the request to running our process_request code. I posted to the google forum and got nothing. I contacted someone at google and they answered back quickly but only said they would contact the team. Nothing since.
It is possible there's something I'm doing to cause this but I really doubt it. Google doesn't provide support so I'm basically out of luck.
If this was a full blown commercial application I'd be out of business.
tl;dr: google app engine has great promise but needs to mature and is not yet suitable for comercial production
