It's due to the lack of airflow and non-constant flow from driving, from what you have explained there is nothing to worry about.If the needle goes right up and stays up, you have issues.
http://au.toyotaownersclub.com/forums/index.php/topic/19545-the-tocau-aurion-faq/ Please look harder in future before creating new threads, there is also a link to the Aurion thread in there.
Well I'm using V6 brakes on mine which is an I4 and the hubs are identical. Not 100% sure if different between ABS and Non-ABS. Most parts will be interchangeable. Just compare whatever you need before you remove the parts.
I doubt there would be, generally the seats and belts are designed to start and stop in specific positions for the seatbelt and other safety reasons.I'm fairly tall as well, so I know how you feel, I just deal with it I guess.