If you are only heaving someone bodily out of an adjacent square I'd call it a Bull Rush attempt, straight up. You roll STR vs. FORT to push the target 1 square and shift into his vacated space.
Either, with the target possibly becoming Prone. (Reflex?)Tripping is part of specific powers in 4e. Do you mean a throw as in forced movement, or a throw as in thrown to the ground? Either way, there are powers for that too.
I find that targeting the NADs with a Grab gives one the leverage to throw someone a proper distance.
I wouldn't believe simple actions like these would be power-only.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.