He gave a rough explanation of the outline of the incident.
大づかみな話で申し訳ないですが、要点は以上です。
I'm sorry for the rough account, but those are the main points.
2
noun, noun or participle which takes 'suru'
grabbing a big handful
Literal meaning of taking a large amount in one's hand. Less common than the figurative sense, but still used in contexts like grabbing snacks or coins.