Kim S unsurprizingly brings a list of papers by a number of different Kim S. (all with different emails obviously). I cant see how I identify which Kim S is associated with which paper when I do "add email"

Are you saying all the papers assigned to the author "Kim, S" are not by the same person?

http://www.skepticalscience.com/tcp.php?Action=Scientist&s=5797

Yes, looking at the papers, there are different first names. (The papers are very different material).

The Web of Science database has not been doing me any favours - there seems to be a few cases where Smith, J is actually more than one person. If you confirm that we have a bunch of papers assigned to one person in the SkS database but in reality, they are written by two separate people with the same surname and first initial, then follow this process:

1. Check that the new author you want to add doesn't already exist in the database, perhaps with a different initial via http://www.skepticalscience.com/tcp.php?Action=Search
2. If they're not already listed, add a new author via http://www.skepticalscience.com/tcp.php?Action=Add_Author - best to enter their full first name to avoid confusion (ideally include the email too)
3. Do a search for the original name via http://www.skepticalscience.com/tcp.php?Action=Search
4. Click on the person's name. This will bring up a list of all the papers assigned to that person
5. I've now added a small (edit) next to each paper's title. Click on the edit link. This brings up all the scientists who co-authored that paper in drop downs
6. For the scientist who you want update, select the newly added author in the drop down then click 'Change Author'

That's it, you will then have reassigned that paper to the newly added author.

I'm currently "having fun" with authors named "Li" and was able to identify two of the ones showing up as "Li, T". I don't yet have their email-addresses but from the publication it would be possible to copy&paste their affiliations. Would it make sense to add these in the email-field or will this just be confusing down the line?

Update: I just realised that I accidentally added authors "Tao, Li" and "Tim, Li" - mixing up the first and last name fields as they show up in different orders on the different screens.