Welcome to the SL owners club. I bought my '86 560SL in October '07. Over the winter months, I gradually got all the nuisance things fixed, by myself, as there are no dealer, or indie mechanics that know these cars, where I live.
Interestingly, the one guy I do trust, who has done some MB work on SL's, also said the head gasket was leaking oil. That turned out to be completely wrong. From little or no maintenance by previous owners, there were lots of small leaks that over time spread oil all over the place, so that accurate diagnosis of the source(s) was impossibly difficult without thorough cleaning of the entire engine, which I did. You should do the same.
The power steering pump has a gasket on the back that dries up and leaks fluid, which dribbles down and gets burned off on the exhaust crossover pipe. Awful mess. The kit is less than $20.00, and can be overhauled in about 2 hours or less, including removal and replacement.
The steering gearbox is a 2 day affair (for the DIY'er) to instal an overhaul kit, again, under $50.00. Adjustment is easy when the box is on the bench. Rebuilt ones are under $300.00 mail order. Mine leaked like a sieve when I got the car, spewing fluid all over the exhaust. Now it's tight and not a drop leaks.
The entire front end suspension, steering related like your quote indicates, like tie rods, drag link, steering shock, idler arm, is easy to do at home. Parts again are cheap and plentiful. (BTW, I'd like to patronize the storefront here, but they don't export outside the U.S. I use ******** AZ and Auto Parts Way in Canada, who have a warehouse in B.C. too).
Look near the oil filter canister and check the condition of the oil level sender gasket. I'll bet it leaks, and I'd also bet someone has tried to seal it with silicone or something. Also look at new valve cover gaskets and probably the oil filler cap gasket, which hardens and lets lots of oil out when the engine is hot.
I guess I'm rambling a bit, but the point is that there are dozens of small inexpensive fixes that you can do yourself or can get any competent mechanic to do for you. At the very least, getting intimate with the car is step 1 toward a cost effective restoration to roadworthiness. All of the information to do the above mentioned tasks is right here on this forum too....

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1986 560SL
2002 Toyota Camry
1993 Lexus