1 If the wipers arms are not of the adjustable type, then you adjust by bending then, As I mentioned previously, use 2 Crescent wrenches: 1 to hold the wiper arm and one to twist the other wrench. Be creative. Or you can pull the Cotter pin and pull out the arm and do it in a vise with several iterations. Watch spacer locations. Getting the arm back in has always been a puzzle for me, like snaking a sewer.
2 Yes I see that someone swiped your toolbox. Make a new one out of an ammunition box. Its airtight. The area in front of the feeder forks is the dirtiest, dustiest part of the running machine.
3 I see you need a deadbolt lock on that back door.
4 Before you hook up tractor power, set the tongue straight, that is not a CV driveline.
5 You are not missing anything from those square bolt holes. I believe they are for adding extra hay flake holdback shields use when doing very light grass and leaves.
6 Yes you can crawl in there with a grinding wheel and sharpen both cutting knives. There are some flathead screws use to hold them. I never bothered to get them loose. If you have a hammer powered screwdriver, that might work. Need a large one, though.
7 Grease the rubbing parts. Thats what they are there for. Plunger has cast iron rubbing blocks on it to hold the plunger in lateral and vertical position. Newer balers use ball bearing races.
8 Yes a shield was there. If the knotter trips while you are there working on it, the needle lift will chop your arm off on the upstroke. Its a clean cut, so just save the parts and have the Doc sew it back on, especially if its your bathroom wiper arm.
9 Looks like the needle brake compression springs are coil bound, Either they are shot and it took a lot of thread to get some damping or someone has a bit too much wisdom in there. Use your fish scale to measure needle lift force as the manual shows. As in NASCAR, coil binding gives the vehicle some great signals as to where max grip is, but some drivers just can't get the hang of it.
10 Looks like those are all the original chains. As long as they are not stretched, they are good to go. If stretched by a jerk (or a Jerk), they will wear out the sprockets. If a chain breaks and the thing looses time, you will need a new pair of needles or a good welder. Use a dry lubricant on the chains. Grease + hay chaf = grinding wheel class abrasive. I just let mine run dry. Many new chains are oil impregnated, anyways.
That's my top 10. Get some good hay bales (3 or 4 ). load the twine. Fire it up, toss in some hay and cross you fingers. When operating, the bale case holds 2 or 3 complete bales. Don't adjust the measuring wheel or bale tension (unless you backed the screws completely out) until you have made a round out in the center of the field.