Is there a manga based on Dragon Ball Heroes? I heard there was a manga based on the game Dragon Ball Heroes. If there is, is it in English, and does it contain the non-canon characters like Beat and SSJ4 Broly?
Yes, there is an spin-off manga called Dragon Ball Heroes: Victory Mission that has been running since October 20, 2012. 

Beat appears a lot throughout the story, the only reference I could find on Broly was in chapter 9 when a Super Saiyan 3 Broly card is played. I couldn't find any licensed English translation. However there are some fan-translations.

The story takes place after the events of Dragon Ball GT.