Not sure that points 1 & 3 can be classed as "relevant" directly to the Cobblers any more? Of interest, yes.
In all points, I suspect risk versus reward is the driver.
Whilst not a legal boff, I am led to believe this length of time is not particularly unusual in this type of investigation? Notoriously difficult to prove the nature of intent at the time of the offence apparently? Whatever that means in the scheme of things?