Is there a way to add all the emails with one domain (ie *.blahblah.com) to a new or existing list?
Sorry but I don't understand that. Can you explain in more details?
You can bulk import subscribers into a list with a CSV file.
Sure... In total we have over 20,000 emails in various lists. I was wondering if (for example) I wanted to find all the emails with the domain "woofwoof.com" and put them into a new list "woof email" or even an existing list?
You can create a segment of the list with email addresses that contains 'woofwoof.com'. Then send emails campaigns to this segment.