i'm wondering should i buy new rott on gog or on steam. i prefer gog, but what will be with mods for game? is possible somehow to download mods from steam workshop and import them manually?

From what I hear, it shouldnt matter.
There will be a ROTT editor with the game, and you should be able to play user mods from either steam or gog.
:)

It has not been released to the public as of yet