Yep, I know of the song as it's pretty much a classical standard, but I never actually took time to learn it all the way. I'm having a little trouble following your description of the tab too, and which parts you're talking about. My easiest answer is to upgrade to full access for $5, and you can watch the series of in-depth video lessons an instructor did for that song (among others), and watch how he frets it throughout.
Romance Lesson

Oh...forgot to mention, it may not be the exact same arrangement, but it is the same song. For instance, I could tell that your tab tells you to hold the 6th string on A at the 5th fret for the bass...but the lesson here (and in another version I saw) just uses the open A string. Generally I'll prefer to use an open string when possible to let it ring out with more sustain, and it's just plain easier at times.