Can someone explain what "Bubbling Under Hot 100" means? Are those songs #'s 101-105?

Sort of. Many of the recurrents could technically be in the Hot 100 right now if they were not removed. Be Without You by Mary J. Blige (#1 Hot 100 Recurrent) would sit at #55 right now if it had not been taken off based on its points. The Bubbling Under The Hot 100 songs are new titles that have not charted.

Bubbling Under Hot 100:

#1 : Number One (Pharrell)
#2 : How About You (Eric Church)
#3 : Down In Mississippi (Sugarland)
#4 : Gallery (Mario Vazquez)
#5 : Why Why Why (Billy Currington)

Needs to hurry and make a debut!

That's the third charted week for your bolded single. You mean on The Hot 100?