Lifko, I'm glad that you found that treasure of a sticky, " General Forum FAQ " by Wolf . Such an abundance of helpful info !
While I easily empathise with information overload, your perusal of gildadorigami is quite valuable, especially frequent visitations to book reviews as well as galleries.
Emphasis might be focused upon models that look appealing and interesting to you for future folding.
The origami database will become easier to use as you frequent it more and more, thus learning more about how to utilize it with each visit.
I would recommend also learning how to order books from origamihouse.jp as well as from origami-shop, in that they will yield a treasure trove of worthwhile books.
You are heading in the right direction by seeking knowledge of CPs and complex models, but I fear that the exploration and enjoyment of origami might be potentially injured by too early emphasis on these topics before developing a sound, patient foundation of intermediate models first.
Essential books:
Please remember that any such catagory will necessarily result in a personal, subjective and arbitrary
selection . There are many, many really good books out there, and these simply comprise my starting point.
The Works of Seiji Nishikawa
http://www.origamihouse.jp/book/origina ... awa_e.html
I fear that this book is fated to go out of print eventually, and is really exceptional .
Genuine Origami by Jun Maekawa
So much enjoyment, so much to learn from one book.
Origami Design Secrets by Robert Lang - Exceedingly worthwhile book, a reference source , but probably better to buy the top two listed books first .
Origami-shop has a special going on now , 3 books of the gift set called , Passion Origami Collection .
http://www.origami-shop.com/en/gift-pas ... -1935.html
From the origami-shop I would recommend anything by Nicolas Terry, Roman Diaz, Quentin Trollip, Bernie Payton and many others on that site.
Many folks , on this forum, might also include Dave Brill's Brilliant Origami as essential . While that is mildly debatable, it is a very worthwhile endeavor and well worth having eventually.
For your mother, especially considering that Easter is imminent, you might consider making the Kawasaki Rose ( with leaves if possible ), Valerie Vann's Magic Cube Rose, or Jun Maekawa's rabbit . There is a video tutorial on Youtube by SaraAdams currently if you don't have time to obtain the diagram. The other listed models are also on youtube .
Origami-resource has a plethera of diagrams as well.
I hope that this has provided at least a thimble-full of ideas toward building a top notch origami library .
If you utilize the references that I've indicated, you will , in time, discover so many more.
Once you have about 15-20 really good books, your quest to identify, locate and purchase the others will naturally fall into place.
I think that we all may be exceedingly thankful for the bounty of information that this forum provides.
Finally, fold whichever model is the most appealing to you personally !