I'm embarrassed to tell you that the option of delaying signal emails is no longer supported. (The "embarrassing" part is that the documentation still blithely goes on and on about the feature, which was removed some time ago. Sorry!)
So, nowadays, since we do not support the delaying of signal emails, then any delay times you specify will be ignored. Signal emails will be sent as quickly and efficiently as possible. (There is some minimal batching done to make the emailing more efficient, i.e. during a flurry of signal-posting activity, we may wait a few seconds to capture more signals before sending out an email, but overall you should assume signal emails are sent as soon as they are posted.)
The paragraph above concerns only the attempt to delay signal emails
going out to subscribers. While this feature is no longer supported, we do
still support delaying the processing of signals -- which is what we call "parking" an order. You can specify that an order will be parked through the use of the parkuntil or parkuntildatetime parameters, as described in the API docs ( http://www.collective2.com/content/automation.htm
You final question asks about the sequence in which delayed orders are processed. However, I can't really answer the question in any meaningful way, since: 1) the delays you asked about were actually email delays, not signal-processing delays; and 2) email delays are not supported any more, in any case.
I hope this answers your question adequately. If not, let me know.