Usually the rear springs sag with age on the E-23s. Check the ride height carefully before you start any work to see where they are at.
The spring compressor is needed for the front struts. There's too much pressure on the spring to just loosen the top strut nut and let it fly!

Replace all the little stuff while you're in there, this means the rubber "rebound" pc, the plastic sleeve for it if it's brittle or cracked, and esp the large lock nut for the strut. A new strut should have a new lock nut with it anyway.
The upper bearing/mounts are all getting old, a new one is a good idea if you're keeping the car.
Watch out for the lower retaining bolts at the hub spindle assembly when R&Ring the strut housing. These 3 bolts like to rust and snap during the job. They're a higher grade of bolt than normally used, Metric 10.9 or something instead of the usual 8.8s. Lots of stress on them from the car. I've had to torch them until cherry red and use Vise-Grip Pliers to remove them if they snap. Usually it's the inner one that's the most trouble.

As for the valve noise, could just be loose rocker arms in need of adjustment, or the cam lobes could be worn too. You have to get into the valve cover and take it off to find out.

I tried Dex-Cool on lots of older BMWs when it first came out, was SO sure that having a silicone -free coolant was the cure for all those clogging aluminum radiators that the owners had to trash from the drop-out effect of the older silicone-based coolant.Here's what I discovered the hard way over a 4 year period on several different BMW engines, all from the '80s vintage.
Yes, Dex-cool IS Phosphate Free, and No Dreaded Silicone either, but, the stuff WILL leak out of ANY possible poor surface or connection in an older coolant system.

This means any old rubber hose surface, pitted metal housing barb,dry gasket or loose clamp connection that you never knew you had with the older "green coolant" comes to light with the Newer Dex-cool.
Chasing down all the new leaks/weepage that you find with pouring the Dex-cool into an older BMW can be frustrating the first year or so.
Colder weather really brings it on too, as the thermal conditions really can bring out "cold engine" only leakage from the side tank gaskets of the composite radiators or housing gaskets on the engine.
I still use the coolant, it's just that I have to warn everyone who wants to dump their old stuff out and use Dex-cool as to what they're getting themselves into. Since you don't have all that silicone additive package falling out of the coolant mix like you used to, there's nothing with the new stuff to adhere to the unknown worn parts of the coolant system that you usually don't see, like the inside of the hose where it's clamped to a metal housing. The old 'Green Goo' of the silicone anti-freeze actually hid poor connections from us with a sort of "Stop-Leak" effect.
Also, the Dex-cool seems to find its way into the cord inner section of the hoses and leaks out the ends of the hose with a wicking effect. The hose end looks pink or orange when viewed.
Not a big leak, but a constant one over time.
Newer hose materials have cut this out for the most part, I think it's called EPDM/EDPM? or something to that effect, it's printed on the outsides of the new hoses.

I end up replacing alot of borderline hoses and hose clamps, along with corroded[you never see how bad they were until you remove the hoses!]metal housings, like the thermostat housings.
Luckily, the heater cores seem fairly immune to Dex-cool so far, as I've never had to replace one for all the reasons that the rest of the coolant system gave me. Headgaskets too aren't a problem,yet anyway.

Use Dex-cool, avoid the silicone build-up of the past, and watch those pesky orange build-ups occur.Always a trade-off, isn't it.

Fluids/oil, the M-30 likes 20w-50 for most seasons, with a lighter oil for low winter temps, like 10w-30. This is esp. true if you still have the older oil pump design that was prone to sticking its relief valve and blowing the oil filter housing o-ring right out of the engine on a very cold day start-up.
The later oil pump is much different than the older design, but you won't know which one you have unless you drop the oil pan, which isn't that easy.

Lots of people use Synthetic oil, your choice on that, don't extend the oil change intervals just because you're using it instead of conventional oil. I'd use Redline or other synthetic trans gearoil in the manual trans. Very good choice to help with winter shifting after first starting the car. Regular gear-oil can be a bear to shift when it's cold.

Change the diff oil too, and pull and grease the front wheel bearings while you're at it if you don't know when they were last done. Sevens kept the older bearing design long after the smaller BMWs had gone to maint-free ones in the '80s.
Didn't change until the E-32 Seven came out with the same set-up in '87-88.
Enjoy the car ..............