On the "Editing member" screen in the ACP, I think it would be useful to have an option to directly email/PM the member from that page.
I would find this useful if I needed to send the member an important message without leaving the ACP.

Perhaps a "Send message" button on the top right of the ACP screen, that opens a popup to email/PM the member.

One does not need to leave the ACP to do it now. I just click on the Member's Name (and hold CTRL down), a new tab opens and I then can send a PM or email from there.

Yes, that's fine for sending a PM to the member, but there is no way to directly send an email to them :)

I just click on the email address on the same page.