1. App Versions are strings, not numbers: So, by version things comes to mind some dot separted numerics. Here in GAE you can give versions like testinstance, dev, live as well which is much more meaningful than http://1.appspot.com.
2. You can batch put, get and delete operations for efficiency So, there may be cases when you have to update 100 entities at once. In that case no need to write the code in a loop to update n entities. There are batch update/delete queries to do that. Please follow here.
3. Datastore performance doesn't depend on how many entities you have: So the jist is no matter you have 100 or 1 million entities in the datastore the retrieval time is same. That is the power of GAE which stores everything in a bigTable. This is really different from mySql, or Oracle databases where number of rows in the table affectes query performance.
Rest you can follow on google app engine blog.