I have a 14 premium edition mustang and it comes with heated seats.
Its one of those things that is nice to have but really not necessary. Ill put it to you this way there are like 20 reasons why i went with premium over basic mustang and heated seats would probably be at the bottom of that list.
My mustang doesnt have a navigation simply because i didnt want it. It was 2000 dollars. I have a note 3 and i installed this in my car Amazon.com: Mountek nGroove Universal CD Slot Mount for Cell Phones and GPS Devices: MP3 Players & Accessories
If i need to use naviagation i put my phone on that turn it to the right and i have a much better navigation then the people that payed over 2000 IMO.
To summarize i would not pay anything extra for the options you mentioned.