The response to the requests uses the Roundtrip format: 2008-04-10T06:30:00.0000000-07:00
where -07:00 is UTC offset which is set on the portal.
In case the portal uses UTC time without any offset, the date/time format in the response will be the following: 2008-04-10T06:30:00.0000000Z.
As for the request, only date can be send in it: 2008-04-10.
If you use the date/time in URL request, colons must be avoided and replaced by hyphens: 2008-04-10T06-30-00.000Z.
Please note that the UTC date and time without the offset are used in this case.
You can get json or xml format adding .json or .xml to the request or pointing the request Content-Type in application/json or text/xml.
Yes. More information you can find in the Request filtering section.