Is it possible to use DateTimePicker (Winforms) to pick both date and time (in the dropdown)? How do you change the custom display of the picked value? Also, is it possible
I'm afraid the DateTimePicker control doesn't have the ability to do those things. It's a pretty basic (and frustrating!) control. Your best option may be to find a third-party control that does what you want.
For the option of typing the date and time manually, you could build a custom component with a TextBox/DateTimePicker combination to accomplish this, and it might work reasonably well, if third-party controls are not an option.