How do I send multiple survey links (at different times) to the same respondent? Would I manage the contact within the same email campaign or under a Global Email List?
You will probably want to have several email campaigns and the contacts can be added to each of those campaigns.
You can then send email campaign one at your desired time. And then send email campaign two at a later time. This is probably the best option to send multiple campaign links to the same email at different times (the different time requirement is the main reason I am suggesting this route).
If you could send multiple links at the same time, the contact could just be added to the same campaign multiple times (using the allow duplicates option).
I hope this helps!