Anyone care to help an old man out?

This is my commuter: 4 miles or so per day. I bought it in ~1993. I'm a very un-handy person, so I have just been taking it to a shop about once a year. At some point it I realized that I'm not a very handy person, so it's just better to give things to people who are handy, and pay them for that handiness.
FFW to today: Not in the best financial position (laid off) and this poor workhorse has been needing routine maintenance for more than 6 months.
Here's my pcpartpicker:
Schwalbe 26*1.75 Marathon Plus Rlx Wire Tire
Shimano Universal Standard Brake Cable Set
Kool Stop Eagle 2 Bicycle Brake Pads (Cantilevel, Black)
Park Tool PPL-1 Polylube 1000 Grease Tube (4 oz)
Muzata Stainless Steel Cable Cutter for Bicycle Cables and Housing etc
The cassette(?) and chain need to be changed too, but the brakes are about done and the rear tire is about bald.
Do I need that cable cutter combo? Are these good tires (all street, alleys with broken glass)? I can manage doing brake cables, right? Can I manage changing the cassette and chain as a sausage fingered twat? How the fuck do I keep the road grime off of this machine? Car wash?
Anything helps.