Can seeds be registered to subscriptions? I noticed there was a "Service" internal name space, however, upon entering the subscription internal name, it doesnt appear in my query results, or what is the subscription area under seeds for?
No seeds are not registered to subscriptions. If you look at table structure of nms:seedMember, you will find recipient and service elements are not connected to nms:recipient or nms:service table respectively. They are a data entry in nms:seedMember table.
The purpose of seed table is to add those email address which does not exist in your email targeting dimension, so that you can send email to them. Similarly, purpose of service in seed address is to verify subscription functionality in your email. That means, if you are providing correct service internal name, then while sending email to seed address it will look for same service from nms:service table. It does not create any record in nms:service table.