2008 CLK550 Aftermarket Radio with CarPlay
 

Trying to work out if I loose too much functionality with an upgrade to CarPlay. I have the MF2541 Harman Kardon HU with Sirius, CD changer in glove box with integrated telephone and ancient iPhone connector in glovebox. I would like to upgrade to a HU that supports Sirius and maintain the HK amp so I don't hav to change out the speakers so will use the MOST adapter for MB. I don't use or need the CD changer, the telephone or the iPhone connector.
I can purchase a double DIN HU like the Alpine iLX-W650 and MOST adapter and would like to know:
1. Can I re-use the existing Sirius tuner or do I need a new tuner and antenna?
2. How do the steering wheel controls integrate? I see there are electrical kits available, hopefully the steering wheel is not connected via fiber?
3. Do I need to add a GPS antenna to use CarPlay?
4. Will the MOST adapter still drive all the speakers?
5. Will I run into powering issues for Main and Accessory power-on/off connections? I thought I read that the fiber connections are used to signal power-on etc...

Thanks in advance

In my 2005 CLK500 I replaced it all (head unit, amps, speakers) so I cannot speak intelligently to all of your questions.

I can say that there is an aftermarket module I bought and had installed to retain steering wheel controls with my new head unit. It was a METRA unit I bought.

I can suggest that IF a MOST adapter exists for the intended head unit then the rest of your gear should work fine with it. I did not try that. In my case one door speaker, and the stock amp both had problems. It was more effective for me to rip and replace it all given where I was with it.