Can I get by without a book for learning my opening repertoire (aside from the Sicilian Najdorf and KID)? My opening repertoire is currently consisting of:

White:

1.e4 

Open Sicilian (5.Bg5 versus Najdorf, Yugoslav Attack versus Dragon)
Versus 1...e5, Scotch Gambit
Versus 1...e6, Tarrasch Variation: Korchnoi Gambit
Versus 1...c6, Panov-Botvinik Attack (don't know much here)

As Black:

Versus 1.e4, Sicilian Defence
Versus Anything Else, King's Indian Defence Setup

I have "Playing the King's Indian Defence" by Everyman Chess which I am currently studying back-to-back, and am planning to do the same with some book (not sure which one to get) on the Najdorf just because obviously, these openings are just so complex and have so many critical lines.  

For the rest of the openings (Scotch Gambit, Korchnoi Gambit, Panov-Botvinik Attack, various Open Sicilian Lines), can I get by without a book and just research and learn thes line I want to play?

I am in the 1400's USCF.
At the USCF 1400-1500 level, the amount of reading you are planning on doing is already far too much. When you play people at your level they'll leave book pretty early; when you play people 400 points higher they'll beat you whether or not you have 12 moves memorized. The theory simply isn't going to matter for the vast majority of your games. Save the detailed reading and memorization until you get closer to 1800 at least. For now just play what you like, and after your game look things up in a database or a nice survey book like Fundamental Chess Openings (and if you want to know the ideas behind various openings, FCO is a fine place to start). Take the time you would have spent studying openings and use it to study tactics and endgames.

Of course, if you get lots of enjoyment from reading opening manuals cover to cover, I don't want to stop you. But it's not an efficient way to improve your results (especially at your current level), and you certainly don't need to do it for every opening you think you might encounter.