I also aquired a Bank-A-Ball quite a few years ago in similar condition to yours.
My cabinet looks to be a bit better than yours, but not by much, but my coin door was way worse than yours. Surprisingly inside the machine mechanically everything was in great shape! Also the play field is pretty nice on mine.
The machine was stored in an old garage, while "protected" from the elements, it was not a great place for it to be.
I used EvapoRust on the coin door, and it came out decent, but not prefect because of how bad it was to start with.
What did amaze me is the coin chutes and the plate around them came out almost perfect, as well as the shooter rod bracket.
I have not yet done the legs, hopefully soon I will get them done, as they are horrible also.
Also for the connector in the head, I asked the same question, and got the same answer. I guess for a few years that is the way they made the connectors just hanging unsecured.
In the short term I cleaned mine up as best as possible, checked basics like fuses and connectors, waxed the play field, fixed burnt out bulbs, added new balls, and it has been a fun game.
Maybe someday it will be my first full restore, we will see.