feel free to skip down to "ISSUES I'M TRYING TO ADDRESS" to get to the meat of this post.
Greetings! This is my very first post but I've been a long time lurker here.
I'll start with a short intro,
I have a 99' 4 Door Automatic XJ w/ 240k under her belt, driven it from NY to WA and back to MI where we live now -the Power Steering went out a couple years ago & I was offered a hand-me-down Passat. [Which led to XJ going unused]

I eventually changed the P.S.Pump w/ a used one from Ebay, along w/ the serpentine belt- I drove it around the block a couple times but didn't want to take her far as I was unsure if I used the proper tension on the belt.That said it ran fine & I've sense determined the tension is fine.
I have VERY limited Mechanical experience, but I LOVE my XJ as it's the only vehicle I've ever been able to service myself & I intend to more and more advanced servicing to it- hence why I'm here to consult you all!
Well, that Passat had a timing issue and it's like 5k (that I dont have) to fix it, so now I'm back to the XJ and am trying to get it safe for daily driving.

Servicing I've Performed previously & in the last couple weeks (to display my limited technical experience)
-Changed the Starter -Replaced the Front Wiper Motor -replaced Ignition Cylinder -Replaced Window Motor on Drivers Side
-Transmission Fluid/Filter Change [which took my *** NINE HOURS in a cold Michigan Garage last week due to the trans-pan/dipstick ect]
-I pulled a new glove box from the JY & finally have a closing GB now!

***ISSUES I'M TRYING TO ADDRESS

IGNITION & KEY ISSUE
For starters... the starter- it works fine but I've been jumping the battery to the starter to start the thing for years, the key WILL occassionally engage the starter, but 8/10 times I'm using the push button switch I've connected by alligator clips to the battery/starter so I don't have to reach down all the time.

Like a lot of Jeeps, you could use anything to turn the ignition, so I replaced the ignition cylinder yesterday & the key started the thing 5 times in a row!!!
However, then the key wouldn't turn all the way back to the point it releases... I took the covers off from the steering column & noticed if I wiggled what I THINK is the "park safety" cable that the key would then turn all the way back and come out. However, it only seems to work until I've reassembled everything. I'm having a hard time finding definitive info on where I can permanently adjust that cable to fix this issue. I've tried shoving the shifter into park to get the key to turn back enough to come out but that only worked one time. Anything you can share with me about this would be GREATLY beneficial!

Front End Suspension / Steering Overhaul
While Under the XJ the last week I was taking note of rust & the general condition of things to consider road safety.
I noticed the drivers side Steering Knuckle is extremely rusted & is probably 1/8" thinner on the bottom due to corrosion. This is obviously a big concern of mine.
I havn't checked the wheels for play but I had someone look over the jeep before I drove it from WA to MI about 4 years ago & they said then the Bearings would need replaced soon-
Needless to say It's time to put new Wheel Hubs / Bearings on & I plan to do it myself. (For the first time)
I noticed pretty much every bushing on the front end is shot, and while it still drives really well I need to replace those.

I am planning on putting new Steering Knuckles, Wheel Hub/Bearings & Ball Joints / Tie Rods ect on the front
(I figure that will be easier than trying to get new bushings on the current hardware, maybe I'm wrong about that???)

I've been researching here & around the inter-webs to get an idea of what that'll look like & if it's something I think I can do.
I do think I can do it, it's just going to be a pain in the *** & frustrating given the extensive rust down there.
I just know if I'm going to be getting down to the Steering knuckles I might as well do everything else while I'm at it. (Including changing brake pads)
What should I look for when inspecting the brakes other than the state of the brake pads?

General Tune-Up?
I havnt inspected the spark plugs or anything but figure it's time to do a general tune up,
issue is I don't know exactly what that entails... Should I clean the Throttle Body & Change the spark plugs? Is that it?

The engine sounds great & is running like the unkillable machine it is, but I want to put the preventative maintenance in
I'm making this post as a jump-off point and to hopefully get some general ideas about these repairs & advice from folks who are experienced with it.

Will add photos of the bottom side of the Jeep when I get a chance.

THANK YOU IN ADVANCE!