1989 300E power steering leak & cruise control

I have a 1989 300E with 710,000km and I have a power steering leak. What are the most common places where it would leak from? I would like to know if it is hard to replace the lines and the pump and if not how do I go about doing this?

I also have a problem with my cruise control. I will put the cruise control on when I am on the hwy doing about 100 km and it starts out fine, but then after about 5 min the cruise control with stop working. I turn it on again and 5 min later the crusie stops. What could be causing this problem?

Thanks

Fab