Hi Jeffrey,
I think its important to separate what a 'Contact" is from a Customer or Lead. Are they new or potential customers or simply the additional contact info for already existing customers or leads? I'd recommend going through our Help Center and specifically our Leads section, to get a better understanding of the breakdown. Also see our videos on the Import/Export Tool as well.
If you are indeed importing contacts for already existing customers or leads, also go through our Importing Customer & Contacts blog post for some great information on how to do this.
As for your notes, I don't think you'll want several contact records with the same name. I would go with the first option and have the one contact with several notes. Keep in mind that there are two notes fields. One in the Customer table and one in the Contacts table. Both fields are 4000 characters, so they should hold whatever notes you need to add.
Hope this helps,
- Adam