Stale Views and Data Size 2

I've been doing some testing on Couchbase. If I insert a document and then use a view to read it back, it takes on average about 1.5 seconds for the view to pick it up. This is when there are less than 10 documents inserted.

If I insert 10000, and then re-run the test (insert document and then use view and keep looping until I can read it back). It takes about 30 minutes.

If I insert 10000 documents, wait 1/2 hour and then run the insert-1-document-and-retrieve-via-view test it take about 1.5 seconds again.

Am I to understand from this that Couchbase writes everything to memory and later on at some indeterminate time it will write to disk?

Are the above test results what you would expect? And what are the semantics of inserting to couchbase? I understand it's asynchronous but what has happened between invoking the call and the call returning? How does the application code know that the insert has been successful and completed without error?

Thanks