I want to understand the ADHD brain science

Please point me to the best resources to understand what we know right now about the science behind ADHD and the brain. 

I still don't understand what is causing all these symptoms or effects. Is it just the issue of dopamine or is there more?

My husband has these issues:

Lack of organization and massive distraction (but only if he is not interested - if so, then hyperfocus)

Lost in thoughts to the point of not hearing me speak - also this is dangerous while driving

Very poor short term memory, and forgets conversations we had and agreements we made

Awful with household chores, cannot pick up after himself, a whirlwind of mess through the day

Definite rejection dysphoria, cannot handle even a scent of criticism even if he is clearly wrong

Trouble finishing projects - we have two houses that he built that are still unfinished

Impulsive decisions, including financially. No planning for the long term, lots of risk taking. 


Is all of this caused by the same brain issue?
 

Thank you