Right now I only have 1 character where i've just been exploring and haven't started any of the fraction questlines or the main questline. So without spoling anything, do I need to have at least started the main quest for this DLC or can you play the DLC without the main quest?

I think you need to have started/completed the Horn of Jurgen Windcaller quest to start the Solstheim MQ.

You don't need to start the MQ to go to Solstheim, but the Dragonborn questline and a few side quests won't be available until you complete The Way of the Voice (meet the Greybeards).

@edit Or, as Silhouette stated, start The Horn of Jurgen Windcaller. But IIRC it starts automatically after you talk to Argneir

You need to complete the Horn of Jurgen Windcaller in order to start the quest. Although you can go to Solstheim anytime.

Alright thanks. Might as well go do that before I buy this DLC.

Is there a level requirement as well?

Thanks.