Power Steering Fluid Leak-- 2000 VW Passat

Ok, so I recently came into possession of a 2000 VW Passat. It has been serviced every 3 months like clockwork, has 258,000 miles on it. Let’s not talk about how I wound up choosing this car.

Ok, so the problem is this: the engine is in really good shape. Runs really well. But there’s a power steering fluid leak, which the VW repair shop tells me means I need to completely replace the rack and pinion steering at a cost of roughly $1300. I know this car will keep running and I don’t mind repairing it, I just don’t think that the leak is indicative of the entire steering system being shot. I’ve been topping it off with fluid every 7-10 days, and it’s running fine, but I have noticed that when there’s a change in humidity, the leak seems to speed up (ie. it rains a lot and is foggy, or there’s lots of heat and humidity). Has anyone encountered this before? Should I take my car to a second shop for another estimate? Am I just trying to rationalize not repairing the car while I’m broke and in grad school?

Secondary problem-- one of the o2 sensors has burned out and the check engine light is always on. The catalytic converter was tested and is fine, but the two problems seemed to occur roughly at the same time. Any idea what to do?