Ok so far ive heard that the dragonborn dlc changes somethings in vanilla game like the cultists and the Hera quest actually showing herma instead of the blue ball of light, etc etc.

Question is, to get the most outta the dlc is it best to start a new game to fully enjoy the dlc or is there basically nothing else changed in vanilla besides the 2 I listed?

Honestly? Some of the new content, albeit optional, is geared specifically for high level characters. You'll have plenty fun starting again too, if you like.

I know that its geared towards high level which is nice, but I was wondering was there any other changes to vanilla skyrim that I will miss by going in on a previous charecter compared to starting a new charecter to experience the tweeks they did to vanilla skyrim.