Robert Wang's book is an excellent Qabalistic primer (as says its name) and does deal with Tarot, but it is more general. It doesn't deal too much with the Thoth in-depth, but more in the general terms of its Qabalistic system. I recommend it together with what I think of its "compnion book," Dion Fortune's Mystical Kabbalah. The two, together with Duquette's Qabalah book, work very well together and complement each other.
Angeles Arrien's book is problematic, and there have been some heated threads about it in the Thoth forum. Its main problem is that, by admission of the author, it deliberately eschews all of Crowley and contains Arrien's own second-hand interpretations. You learn a lot mainly about Arrien herself in the book, less so about the Thoth and Crowley. I can't really recommend it based on the simple reason that if you want to learn about the Thoth, it makes little sense to work with something that isn't Thoth. While I don't like her book in any case, I could see someone getting something out of it, as a compilation of alternative interpretations, after they've gained some basic familiarity with the deck.
Ultimately, when studying the Thoth it helps to remember that it is a system, and everything is interconnected. Once you learn a few Kabbalistic definitions, they apply to all other aspects of the deck and you can really start working with the system on your own. It really isn't difficult, and is well worth it. Someone here said you can't hurry study of the Thoth and that's true, but you can try to breeze past the underlying system in order to get it over with and then move on to really getting a grip on the deck itself.
Kabbalah isn't the main thing, it is merely the language in which the deck expresses itself. While I do see it as a necessary stepping-stone, don't get bogged down by its minutiae because you will have ample opportunities to work with and understand your tools better when you move on to the deck. Get the basics down and move on, then look at every card through that lens and not only will things then "magically" start to make sense, but with every card you analyze in this way your proficiency in the deck's language will improve.
I found the BOT completely and utterly impenetrable aside from providing information, mostly cryptic. Having slurped an attempt to eat some Kabbalah soup, skived astrology stew and stomach boggled with alchemy pudding... FINALLY... I briefly hear talking - patient and considered, even kind?? 
