Steering rack leak question

[Martin Suryadarma]

Hi Audi experts,

My car's steering rack has been leaking for the past 2 years, but I think
it's getting worse :(. It leaks on the left side of the rack (if you're 
facing the engine bay) and drips on to the exhaust pipe, which is hot and
burns the mineral oil, so I get smoke outside the car from time to time.
My questions are:

1. Can mineral oil dripping on hot exhaust create fire? Or just smoke like
has been happening?
2. How many hours of labor approximately does it take to remove and
replace this? The reason is, I will have my mechanic fix this, so I just
want to have a number from you guys before I ask him. 

Thanks a lot!

Martin

PS: Car is 1989 Audi 100.