Sharepoint 2007 date time in a list

We are using a custom list on Sharepoint where we require users to enter data with a date and time field. We have been facing huge issues in data validity when generating reports due to this field. Following are the kinds of mistakes:

1. Selecting AM instead of PM or vice verse. Changing to 24 hrs format doesn't help much because then the users select (as an example) 02:00 instead of 14:00 for 02:00PM.
2. There are errors regarding formats of dates, hence some entries have dates from the future or the past.
3. As the reports are generated each week, the list needs to be populated by th开发者_如何学Pythone end of the week. If the month has changed between the week, people forget to change the month in the calendar and the entries are of the last week of the current month instead of the last week of the previous month.

Are there ways to configure the list(Pref. without programming) so that:

A. Only working hours are available in the time related dropdown.

B. Dates from the future are not allowed( Or not available)

Any help would be appreciated.

As far as I know, you won't be able to satisfy these requirements with no custom code.

If you decide to go down the coding path, what you need to do is create a custom field type. Let me know of you need help on this.