Sounds like episodes from Friends and Home Improvement!
https://youtu.be/pMuVm1Y669U?si=QlVkAb6OxP82QrsK
https://youtu.be/I6vcQHlpwVA?si=70Ah5DQRaqvMUId3
(Bucks dog house outside.)
Wiring varies depending on where the light comes into the circuit, beginning, middle, or end of the run. I usually start by removing all the switches and identifying each wire with a volt meter to find the hot leg and neutral, then continuity to identify which ones would be travelers and switch legs and wires to the light.
I've spent a lot of time over the years tracing out and re-wiring 3 and 4 way switches for friends. Many times after the house was painted and the painters removed and reinstalled the switches. Insulation colors do not necessarily have a set meaning. As mentioned with the white wire with black tape.
The switch names can also be confusing. 3 way basically control from 2 locations and putting a 4 way between them controls 3 or more locations. My brothers brand new house caused a dead short when you turned on one of the light switches in his daughters bedroom, and a friends house they used the bare copper ground wire as one of the travelers because they ran a 2 wire romex instead of a 3 wire.
The NEC has also updated the electrical code requirements on new installations. In the old days you could have a switch box with travelers and a hot or switch leg. Now, with a few exceptions, switch boxes require a neutral also.
The garage wiring sounds interesting. If you are shutting the main breaker to the panel and that stays on something is weird. A circuit tracer would help find where the power originates, but it can be a challenge.
The guys that own the local Porsche shop told me he had a problem. He said when he turns on the light switch in the house to the detached garage, it works for about 10 minutes and then the breaker trips. When I opened the box in the garage, I saw one of the things I hate in older homes. Nothing more fun than working with wasps nests and crumbling insulation. A weak splice can lead to heat build up and eventual fire or tripping of a breaker. Similar to what happens to homes with aluminum wire.
