I have a 2006, original gen macbook. I’ve had similar issues to you. These machines don’t boot from USB’s in my experience. Burn it to a DVD, you’re issue will probably be resolved. It worked for me. Also, I think your system has a 32 bit UEFI but has a 64 bit processor. This can cause many issues. Personally, I got linux on my machine so I had to use a modded 64 bit linux distro that would work on a 32 bit UEFI. If you want a link to that, I can share it as it would most definetly work on a DVD. However, Mac OSX is a different story. You have to make sure you’re using a 32 bit distro, aka, the right OSX version. And on a DVD of course, since no boot from USB on that system.
Not going to pretend like I’m an expert on cars, but, a grinding noise when you are in park and the car shuts off when put in gear sounds like a transmission problem. Also, check if the steering wheel is hard to turn. If it is, then the hydraulics have something wrong too. Pretty sure it’s not solely an ignition problem, since you had that grinding issue however there probably is something wrong with it if your key won’t turn easily. Find yourself a pro my friend