Disconnecting the driver information center/stereo

I'm not sure I understand what you are disconnecting. Can you explain?

The car should run but you might get trouble codes because the CAN has been interrupted.

Starting in 1994 GM began refusing to sell radio service manuals and parts because they wanted to lock up all of the repair business for themselves and their grossly over-priced service centers. People countered by just buying higher quality aftermarket replacements. To prevent you from doing that, beginning with the 2002 models, they started building the Body Computers into the radios so you could not remove them from the vehicle. Without it you won't have cruise control, power windows, and many other functions. The aftermarket industry now makes "radio relocation" kits that let you move the radio to the trunk, and cut the speaker wires and run them to the new radio. If you want to avoid that, you're stuck with the products you can buy from the dealer at about two to three times the cost for the same features as a nice aftermarket radio has. The new radio from the dealer will also have to be programmed to work with your car and of course they don't do that for free.
They often have upgrade radios on display in their high-pressure showroom, otherwise the guys in the parts department will be able to help you select a new radio.

Can't give you any advice on that. GM will not allow us to buy radio service manuals or parts since the '94 model year in an effort to lock up all the repair business and cut out all the lower-priced independent shops. What I CAN suggest is there's a very good chance this box will work but I suspect it will still have to be programmed by the dealer. The port on the back of the radio they are referring to was recognized automatically on older radios when something was plugged into it. Each time the radio was turned on, it checked each port to see what was connected, then made those devices active, but there's no money involved in that so on newer radios those ports have to be "turned on" by changing the software. That is done by the dealer, ... For a fee. I'm more familiar with Chrysler products. They have the same kind of ports but nothing needs to be programmed and no visit to the dealer is required. You just plug things in and they work.

You'll notice on the vehicle listings, all the models listed go back to 2002 models. That's when GM started building these radios that can't be removed from the vehicle because that removes the Body Computer which controls power windows and cruise control among many other things. That ties you to their high-failure radios which are very expensive to repair.

Most of the newer Chrysler radios now have two external ports on the back so they can be connected to satellite radio and another device. I see in the listing for this box there is a way to switch between the box and satellite radio if you have it but it doesn't say if the radio needs two ports. If nothing else is connected to your radio, that shouldn't be a concern.

Turn off radio, hold up or down arrow until it beeps. Down is for hour and up is for minute.

That's a good question. Has the problem been resolved? Also, keep in mind that between 1994 and 2004 there were a lot of changes.

How did you change the time before? You may not be able to with an after market radio.