Hi there, Thanks for using justanswer.
As far as the spare is concerned there's 2 things that restrict what size spare tire/wheel combo can be used on the factory mount.
Diameter and tire width are your primary concerns here as anything too wide wont allow you to secure the factory mount and anything to large in diameter will hit the bottom bumper.
One thing you can do is measure the diameter and width for the OEM 20" Le mans wheel and tire. Then measure the 18" spare you have equipped now and calculate the differences (if any). If the 20" wheel tire combination is larger then measure any available space between the 18" spare and the rear bumper to see if there is enough available room.
The other option would be to just remove the spare that is on there now and fit the 20" wheel your currently driving on to the spare tire rack and see if it fits. This is what I would do. I would imagine it would fit, because it's common practice when replacing a blown tire to put the blown one mounted to where the spare was to get it to the garage for replacement.
As far as your bluetooth and ipod connectivity are concerned I would like some more clarification on exactly what your trying to accomplish. Are you asking if there is bluetooth connectivity for your phone on OEM equipped a/v unit? or are you wanting to know if there is an aftermarkey piggyback system comaptible with the OE unit?
Let me know and I will do my best to assist you.