I am not going to say I know this 100% but the Kona must be very similar. All of the I5s do support Android Auto (AA) and there is no cost because the data used is part of your own cell plan.
As for the Heads Up Display (HUD), the Kona's HUD display functions normally when using AA. Setting a destination in Google Maps or Waze does not show up on the HUD, but setting a destination on the Kona's nav first, then load AA and set a destination in Waze, I get Huyndai's directions shown on the HUD as well as the Waze's on the display. Under all conditions the Kona's HUD shows street sign indications for things like school zones and speed limits. This is very useful if you don't know what the limit is where you are and is independent from AA. As a side note, integration of the HUD and AA would be very cool as I prefer Waze and would like to see warnings for speed traps and accidents ahead.
Hyundai was talking about a subscription fees after 3 years for the Bluelink service, which is a different thing altogether. It provides Hyundai with telematics data and gives you the ability to remotely do a few things like open doors and set climate, charge rate limits or locate your car. The Konas come equipped with a 4G SIM card. In my opinion they should be paying you for your data, not you paying them. There was an interesting thread on the Kona forum about "Going Black" or removing the data connection to the Kona. I tried but could not find the link. I seem to recall it being someone in the NorthWest, possibly
@Esprit1st as the instigator.
Does the I5 support wireless AA ? I do not know but once you've tried wireless AA you will not want to go back. Currently I use permanently plugged in cell phone just to run Waze on AA. Plugging and unplugging a phone for AA gets old fast and seems SO yesterday. I hope the higher trim models like the Ultimate support this feature as they do on similar newer Hyundais. Please chime in if you know of wireless AA support for any trim levels.
For the Kona, NAV updates come about 4 times per year and may include changes to the radio or entertainment system that may be good or bad. We have had a few ugly ones. Hyundai really is disadvantaged when it comes to software.