There is a Magic Eraser that has no soap or cleaner, it's just the melamine foam pad and it is all white. They scrub effectively if you need to, can be used dry, and probably not as abrasive as scotch pads. I have not tried them for cleaning track.
This is what we’ve been having decent luck with on old Marx tinplate, except we’re using the thin sheets that come eight to a “book.” Because they’re so thin, they’re easy to use on anything that isn’t flat. Cut a piece of one of the sheets and go over the engine lightly, no scratches and all the miscellaneous crud lifts off. It’s actually more convenient than baking soda (but I’m still nervous about trying it on anything with delicate decals or soft paint.)
We’ve always used alcohol on track and engine wheels and haven’t had fire problems. Don’t soak anything and do let it dry, no biggie.