No. It is part of the space treaty that most nations have signed up to, that any part of a space craft remains the property of whoever launched it, and clean-up of it is the responsibility of the country from which it is launched.

Once burnt, yes, safe greenhouse gas. At least, no worse than any other combustion products. I mean, it would be nice if hydrogen wasn’t such a pain, but we have to work with the universe we are given.

Methane leaks need to be contained to the amount practical, but they are doing that.