There are few things more educational than an old car....
Order of safety... 1. brakes, 2. tires, 3. suspension, 4. belts, 5. Wipers, 6. heater (to defrost the glass)
Where are you? Possibly a mechanical mentor could save you a lot of re-work and wasted $, as well as giving one of us old guys a chance to feel young and useful again.
Do you have any knowledge or experience with wiring, hydraulics, etc.... Helps us use terms that mean something...
Topic = steering wheel:
1. Yes a grant, they are fine, its main job is to turn the shaft which it does fine, the horn setup is a bit cheap but works fine if you are willing to work with it.
Personally $ for a wheel is not an issue for me at the moment, but I still went with a 100$ Grant 13" so I can get my legs under the thing. I did add a $160 custom leather wrap which makes it look as good as any wheel. Point being, cheaper to fix what you got.
2. Likely the problems are between the collar you took off and the contacts inside the steering shaft. Take the aluminum block that has the splines that grab the steering shaft, turn them over and let us have a look... Take a pict of the steering shaft without the wheel on so we can see the contacts.. Possibly the contacts in the housing need replacing, or a new grant mount kit.
3. I do no think the kit you bought will help, as they belong on a factory wheel, not a grant.
4. You have the "upgraded" meaning better looking horn button that kinda clips on the fiberglas horn disk and is held by foam tape/glue... The cheaper looking grants actually have some bumps that have to go past the cuts in the fiberglass disk and then rotate to stay on... I have one of those on at the moment, bought the upgrade, was surprised it did not hook on as well as the cheaper stamped one, and am trying to decide if it is worth it.
5. To test the car's horn separate from the wheel, there should be two contacts that rub against the collar I mentioned on item 2.. if they have electrical contact, the horn goes off. It is possible the horns have issues, but... most likely the connections mentioned on item 2..
6. While I have used the temp button "door bell switches or whatever" as recently as a couple of years ago, I would really discourage you from digging into the wiring. If you choose to go that route, run totally new wires so you can easily remove the whole circuit and do not hack into the original wiring.