MP3 Factory Radio

I have a 2001 Monte Carlo LS with the non-Bose, double-DIN size AM/FM CD
player. I was going to replace the factory unit with an aftermarket head
unit, but found out that the previous owner had already replaced the front
speakers with a set of high-end Pioneer Premier 6.5 component speakers and
the rear speakers with a decent set of 3-way Kenwood 6x9's. For some
reason, he removed the 1" tweeters from the components up front, but I had a
set of Pioneer tweeters I bought for my old car and reinstalled these up
front. With the mids and high-range now sounding very good (for a factory
head unit, that is), I decided I would add the 12" Memphis Audio sub I have,
powered by a 2 ch. 400 watt Boss amplifier bridged. I took advantage of the
factory wiring already there and unused for the Bose amplifier and used this
to wire up my Boss amp, which saved me alot of headaches as far as running
heavy gauge power wire from the battery back.

Now, I'm quite happy with this setup and as I said earlier, for a factory
head unit, this stereo sounds very good, especially turned up loud. I chose
not to replace the factory head unit, mainly because I did not want to lose
all of extra programming features and the ability to reset the tire
inflation monitor. However, I would be interested in replacing the factory
head unit with a newer factory unit with the MP3 support. What I want to
know is are the newer radios compatible with my car as far as the wiring
harness goes? Also, I know that you need the VIN from the car you pull the
radio from for Theftlock purposes, how much does it cost to have the dealer
reprogram the new radio? And, is there any way for me to reprogram the
radio myself, with the factory VIN, or is this dealer-only?

Thanks for your help.
Sharky