You're usually right on the money Shmoo, but this time I need to offer a correction. These days "regular" FPs and FP+ are the same thing, FP+ was simply the new name introduced when MagicBands and My Disney Experience was launched, so FP+ isn't anything special tied to the
DCL ticket. You're correct with the first explanation about only being able to do 3 FP+ reservations, and then another one once they have been used.
What the DCL ticket gives you is three "VIP" FastPasses, meaning you can cut the line at any attraction without a reservation, but these are strictly limited to 3 for the entire day. There's no extras once they have been used (I explained it a bit better in reply to Neptune's post above).