06 Sonata Electrical Problems! HELP!!

I have a 2006 Hyundai Sonata GLS 3.3 liter.
I've had my Sonata for a few months.
Bought it from a private party. I've had
practically zero problems out of it since I've
had it. Just routine maintenance. But since
I've owned it I've noticed little things such
as:
-Headlights dimming and loss of air
pressure from the air vents when I brake
and get below 30mph.
-My steering wheel controls have switched
up on me randomly. Like the volume up is
suddenly the mute button and the mute
button is the mode button ect. (Only
happens a few times)
-Interior dome lights flicker when the car is
on.
-Slight transmission issue. For example,
When I have to slow down to stop at a
stoplight and the light turns green before I
make a complete stop as I accelerate the
transmission acts confused. Like it doesn't
know if it should be in 1,2 or 3?? It doesn't
act up in manual mode....
-Most recently my passenger headlight
went out. Not my bulb. I'm assuming the
wiring leading to the headlight has a short
in it. (If you move it around it will come on
but the second it falls back into place it
goes back off.)

AND NOW MY MAIN CONCERN RIGHT
NOW:
The car isn't wanting to start. Its Nov. Just
started getting to freezing and bellow and
the car just doesn't want to start! It will turn
over for about 30 seconds to a minute
before starting or not. I've had my battery,
starter and alternator tested and all came
back perfect. Which leads me to believe
something electrical like everything else
wrong in the car. I love this car but I've
never had to deal with this stuff. There for
leaving me in the dark and not wanting to
go to a dealer where they'll charge me just
to say I'm crazy and nothing's wrong when
clearly SOMETHING is. Please help!!!