I always assumed that there was a combination of gravity plates (like on Star Trek Enterprise) and a mix of some form of gravity engine on the ships. Who knows, maybe in the future artificial gravity machines will be developed. Although as Jinx said, considering other sci-fi genres, Freelancer isn't that far in terms of technology.
EDIT: With tractor beam technology, I always assumed that was a mix of magnetic waves and a mini-transporter. Maybe they only use it for small items transporter wise? Like early Enterprise style. Still developing.