how to make Firefox import data from seamonkey (bookmarks, passwords, etc etc)
Firefox code ought to be able to import data from an old Seamonkey or Firefox profile as well as data from other browsers such as Microsoft products. My Seamonkey profile isn't even old. I'm using the version compiled about a year ago because the two more recent ones crashed occasionally.
There presently doesn't seem to be any code in Firefox to import data. Supposedly there used to be. It's still needed or very desirable.
I don't have a question because it's pretty clearly not there. It's something for you to fix.
Wšykne wótegrona (1)
You can submit the idea to add the ability to auto-import data from SeaMonkey at Mozilla Connect.
Honestly though, SeaMonkey is not a very popular browser, so I doubt it's high on the devs' priority list.