2 questions regarding spartan ops

If someone from 343 could provide some answers to these, as vaguely as possible if necessary, it would be much appreciated

1. What is the target length and span of a single Spartan ops mission?
Will we be seeing very short missions focused on a single area or will we be seeing more of the lengthier missions that take place over multiple battlefields

And 2. What happens after the main story is finished?
Will we see other follow up stories or will it be more of a one and done thing?