Thank you for writing.
1. Here is how to achieve the HH:MM AM/PM format.
radDateTimePicker1.Format = DateTimePickerFormat.Custom;
Features #2 and #3 are still not implemented:
2. limit the time that can be chosen (e.g. 8 AM to 5 PM)
3. set the interval of increasing and decreasing the Minutes part to 30 instead of 1
As my colleague Boyko has mentioned these feature are added in our list, but we still do not have a specified time frame for them. They are added to our Public Issue Tracker as well and you can add your vote for them here
the Telerik team