Where are you located? That oil is a bit thick for an engine in good condition, unless you live in a hot climate.. As your bearings and other internals wear over time, a thicker oil helps to quiet the engine and will raise your oil pressure slightly. A m42 in good condition will like 5w40, or 5w30.
Manual Tranny Fluid=ATF
What are Bosch High Performance Plugs?
Don't just check for loose bolts. While you're in there, go ahead and remove the internal bolts and re-install with loctite. Make sure the male and female threads are clean before you apply loctite.
After installing your new hoses, get a can of spray carb cleaner with the red nozzle extension, and check ALL of your connections for leaks by spraying a small amount on each joint. You will know when you have found a leak, as the engine will speed up. Also check your upper and lower manifold gaskets using the same technique.
Your brake and clutch fluid should be replaced and bled every 2 years, You might as well do both, as they share the same reservoir.
You might want to go ahead and perform the throttle body heater plate delete while your manifold is off. Do a search for that info.