1) I don't understand their pricing scheme, does gamfeed use the free or the paid? (because currently I'm seeing 2 price lists: http://code.google.com/appengine/docs/billing.html and http://www.google.com/enterprise/cloud/appengine/pricing.htm...)

2) AppEngine Datastore: have you ever need to modify your model in a way you have to run a transaction over a large number of rows? If yes, would that hurt? (or, another case is if you had encountered a bug in your code that mistakenly recorded the wrong data thus you have to "clean them all").

3) I saw your code regarding code optimization, would that cause the code to become a bit brittle by not encapsulating the caching somehow? Like, spreading the cache at various level in your code.

Thanks!