Need Help Registering A Second Hand Car / Bike

Recently I purchased a second hand motorcycle and car.

Have been trying to get a straight story regarding what the process is for me to register these vehicles in my name. My Thai friends are all giving me different stories about where to go and what to do.

Both vehicles have stickers that expire in 10 months so I am assuming I do not get a new plate or sticker. However I am being told that both vehicles need to be inspected by an engineer at the registration center. This year the car had a steering upgrade to power steering and apparently when I go to register the vehicle I will have to pay 3 or 4,000 baht tax for this upgrade?

As well do any of you have experience with purchasing insurance for a car – my girlfriend tells me there is no such thing as 3^rd party insurance and says even with the best insurance package I would still have to pay to repair the other persons vehicle if it was my fault. Are insurance rates similar for foreigners and Thais or would it be a financial advantage to have the insurance in my girlfriend’s name?