Do most of my maintenance myself for the minor stuff like fluid and filter changes. For more difficult jobs, I head to my neighborhood mechanic, a lot cheaper and does a better job than any $tealership.
Colder air causes air to become more dense and makes it seem to the sensors that the tire has lost air. Just air them back up to what's stated on the driver's side door jam, usually 32 PSI or so, and the light should turn off.
First, make sure the shift lever is all the way into the PARK position. Second, you say the battery and starter are good. How do you know? Did you have them tested? If your battery is older than 4 years old then I would replace it.
So you not understanding how to operate a switch will make you not by a certain product? That's some great reasoning there. Maybe pull out your owner's manual and learn how to actually use the car? Just a thought....
Well, there could be a whole host of other problems then, like bad tie rods, endlinks, out of round tires (have you tried rotating the tires yet?), different size/brand tires, worn shocks etc.
There is no similar vehicle here in the States that compares to the Avensis. The Avensis is built in the UK and is mainly for the European market.
http://en.wikipedia.org/wiki/Toyota_Avensis