The empeg is just (more or less) like any other high end audio deck. It has no amplifier built in (like high end decks) and must be used with an external amp (like you already have). You can easily install it in place of most other decks in most cars. But you obviously will no longer have CD, TAPE or RADIO.*
*There is a radio module available for the empeg but it currently sells for market price. Market price is very high right now.
Random Play: Very good. It will never repeat a song if that's what you're worried about (unless you have duplicates or the same song linked in multiple playlists). It can make a list from the entire contents of the player or any list you have previously created (lists can be thought of as virtual folders for organising). It can also generate dynamic lists on the fly based on search criteria (and you can shuffle that too). There are multiple shuffle modes as well to apply various weightings.
Car bay: Already mentioned. Standard DIN. You car may or may not be DIN, but trust me, you'll be able to get it in there. Whether you can have TWO decks is what you might want to consider if you plan to keep your current one (the empeg/rio can be played through the aux inputs of another deck, or it can have another deck play through its inputs - or neither if you prefer)
Visuals: Customized visuals cannot be made at this time. You can change the pictures for some of the existing visuals though and can make new dances for the dancing stick man visual.
Upgrading: Software and logo upgrading is simple. VERY VERY simple. It's just a matter of a few mouse clicks.
Discontinued: It came before its time. The market is still not ready for something so cool. It may never be ready for something with this level of hackability. It certainly was not ready for the original price tag. There's more money to be made by selling technology and making product for other companies that are already big players in car audio.
Canada: I'm in Canada too. There's nothing you can do about the exchange rate. You can look in the forsale section or look on ebay. carplayer.com and funmp3players.com might still have some units too. Do not under any circumstances get it delivered via UPS. FedEx if you don't mind paying for shipping and like the tracking number, or POSTAL if you want a decent rate. You can low-bal the value for customs with both of them and specify that the item is a GIFT. But you didn't hear it from me.
Regular IDE: Yes. If by "regular" you mean a regular 2.5" laptop IDE drive. It can hold 2 2.5" drives. All current drives seem to fit. They mostly work together but some people have had issues with certain combinations. pricewatch.com is a good place to look for drive prices. Also the forsale forum gets regular updates of cheap price sightings. look on eBay as well.
Radio thing: The external radio module is (rather) simple to install. If you can install the empeg, you can install the radio module. Check the FAQ. You should read the FAQ for many other reasons anyway.
Newbie: No problem. As mentioned, check the FAQ. It addresses nearly everything in here.
If you want to see a comparison of units, also check out
www.mypocket.com/mobilematrix
Bruno