CD to NAVI upgrade?

[Alscape]

Hi any helps would be greatly appreciated.. I' have a 2.0 cdti exclusiv estate/tourer

After much deliberation I recently bought an Aftermarket Unit from eBay, from the outset I was very happy, I fit it myself although it took a little longer than expected!! I had it checked by an auto electrician who said it was all sweet, it was just what I wanted.... 3 weeks later driving through Germany it died on me, as you can imagine I wasn't best pleased. Anyway no radio or sat nav for a weeks worth of driving in Europe wasn't great. I've now returned and got a refund thanks to eBay.

So now I am at the crossroads, try another import aftermarket or upgrade from my CD400 to a NAVI600/800, this is where my knowledge ends, I am a complete novice when it comes to this so any input would be great!!

Is the conversion possible?
And if so,what components do I absolutely need; fin, navi dials by handbreak, usb etc are these necessary(I have the aux so usb not too much trouble)
I also assume I would have to retrofit Bluetooth or does this somehow come with the navi??

Thanks in advance

[ChromeOrange]

Can't help with what you need etc but I can tell you that I have the Navi900 and I'm very disappointed with it. The navigation won't find addresses from contacts or when entered in to the screen. I can only get somewhere if I add use just the postcode. It finds my phone and plays music via bluetooth but sometimes it will start playing music even if I haven't asked it to and it never starts where I left off when I got out of the car. I actually needed the navigation a couple of days ago when two junctions on the M56 where closed and I was unsure of where to go, it let me down.

I was hoping to upgrade to a carplay unit when the 2016MY came out but it doesn't look like that's possible.

TL : DR - Nav900 is not a great system.