Douglas asks:

Should I check both boxes it gives me, or just the top one that's checked already [on this page]?

The simple answer: go with what it gives you, unless you know a reason otherwise. Jäger goes through a step called discovery which tries to find out what you're really subscribing to.

For example, if you drag in the link "http://blog.davidjanes.com" (or even "http://blog.davidjanes.com/index.xml") it knows you are really subscribing to "http://blog.davidjanes.com/" (note the trailing slash) using the syndication feed of "http://blog.davidjanes.com/index.xml". This one you are "really" subscribing to is the one that will be checked in Jäger, the link that you actually dragged in will be unchecked, just in case you really did mean that page.