The high pressure line is the big hose with banjo (bolted) fittings on each end that goes from the PS pump to usually a metal line that then goes to the steering rack. In other words the hose doesn't hook directly onto the steering rack but rather onto a metal hard line.
Replacing the hose shouldn't be more than a couple hour job including replacing the fluid (you'll drop all the fluid out once you pull that hose). I suppose the reason PS pumps fail is probably more due to the fact of lines bursting or leaks happening that you run it out of fluid, rather than it being a bad pump design.. If you run it out of fluid and destroy a pump, not really fair to blame the pump for that.
Steering rack would be a little more complicated to do, probably more like a 6-8 hour job. I believe you have to support the engine and lower the engine cross member which means a lot of disassembly or at least unhooking of suspension components, plus you'd need an alignment afterwards since you're unhooking the tie rods from the steering rack. If the rack seems like its operating smoothly but just leaking slightly, it's probably not worth messing with, especially since it sounds like the car is gonna be completely destroyed by the end of the year...