Yes, you can configure multiple Email Address to the same Department. While adding Mail Account under Mail Server Settings, associate the Department name. For example, you can associate xyz@zohocorp.com & abc@zohocorp.com to a single Department, so ...
Yes, a support rep can be associated with multiple portals. When support reps log in into Zoho Support they can find a list of portals they are associated with. They can choose between the portals to work in Zoho Support.