The "always in slightly above his head" aspect of Indy is incredibly important. You have to have the right comedic chops to pull that off. Someone too cool can't play Indy.
I'm up for more movies, but I've already seen Raiders and they did it right the first time. I want to see new adventures. They don't need to reboot, just recast.
I'd still prefer an animated series over live action.
Whether it's animated or live action they really should start where Young Indy ended in 1920. Don't reboot, just fill in the gaps. My choice for a live action younger Indy is Jack Quaid.
the soaking would be for fountain pen ink, something like Carter's Ink Eradicator. they don't make that anymore (EPA). For Typewriter ink you can still get typewriter erasers, Amazon.com
but they operate via abrasives. you might be able to experiment using tiny amounts of various solvents...