The miles are high for the year. It equals more than 18000 miles a year the average person does 12000. The timing belt should be done at 75000 miles 150000 225000 etc... they on average last 90000 but it doesnt hurt to replace it before it goes and ruins the water pump and heads. The smell your are experiencing could very well be the brakes. They would make a sulfer/rubber burning smell. It could also be the serpintine belt. The best thing to do is bring it to an Audi shop and have it looked over. They shouldnt charge you if you tell them you will have the car serviced by them. The car sounds like a good buy. here are some websites that should help you price it .
http://www.nadaguides.com/usedcars.aspx?LI=1-21-1-5013-0-0-0&l=1&w=21&p=1&f=5014&y=1999&m=1190&d=200&c=20&mi= 165000&vi=1575&z=03885&da=-1
Kelley Blue Book - Private Party Pricing Report - Audi, A6