What reading materials give in-depth coverage of baking with gluten-free ingredients and techniques?
The reason behind "Gluten-Free" as a buzzword? Humans can be allergic to gluten strands. Unless you are using a recipe that is having low gluten or high gluten content related problems (too soft or hard due to gluten bonds), the only reason to reduce gluten is to accommodate someone's food allergy. In which case you need to eliminate gluten altogether. Many people who have severe reactions simply will not eat food unless they know it was prepared correctly. In a very American twist, I have met some of those people who are not allergic to Gluten, have no sensitivity to it, and treat "going Gluten-Free" as if it were something other than a dietary restriction; more like a lifestyle or weight diet than one that keeps your body from attacking itself. 


I can't offer more actual advice for someone with a gluten-allergy related disorder like Celiac's that go work with a physician and get instruction from a real dietician.
For a straightforward approach to learning to bake with gluten-free ingredients, Google has plenty of resources for you to use, like this primur. 
For an explanation of typical ingredients, their uses, pros and cons, Living Without has a well-rounded article
Additional ingredients, techniques, and strategies for serving and preparing are covered in the cookbook Gluten-Free Quick and Easy by Carol Fenster, PhD, who develops products for Bob's Red Mill
You would be best served with any further requests for detail on specific ingredients asking about them in particular rather than holding out hope for a vague guide to all Gluten-free ingredients. 

This is because items like xantham gum, agar and so forth are only Gluten-Free by coincidence, and you will be crowding out other helpful resources (i.e. if you look for tapioca starch uses, but in a Gluten Free article, you may easily crowd out the myriad vegan resources that reference it's use)



Like any restriction, best practices are input control-based: (1) referencing what contains wheat or gluten and (2) making sure you don't buy any by reading the ingredients. In addition to actual gluten-specific sensitivities, the Candida diet requires that adherents avoid grains due to immune reactions to gluten (this is semi-dubious in that this is applied above and beyond the scope of defined allergy). In terms of any guide to gluten-free'ing your foods, it isn't that complicated. Basically you need to develop a back-catalog of substitutions. There is less concept, more trivia.


The degree of elasticity in bread is determined by its gluten content. In many problem-solving questions you will see offered that vital wheat gluten or other 'hard flours' can be added to doughs needing more gluten, or that 'soft flours' with low gluten can be added where a dough is coming out too chewy. 


In replacing gluten-containing ingredients, there are many substitute flours like Amaranth, Brown Rice, and Garbanzo flours that contain no gluten whatsoever. 
To substitute APF, Grape Seed Flour is one, a combination of rice flour, tapioca flour, and corn/potato starch can also be made to replicate APF.

How to substitute; Each of the different flours has a different taste (garbanzo flour is nutty, corn flour tastes like corn) and texture (vital wheat gluten can replicate chicken flesh when cooked as seitan; or consider the difference to the tooth between white, whole wheat, and semolina flours). For gluten containing flours, each also has varying levels of gluten.


Assess the taste and texture characteristics of the flour you will be substituting, match them to one with the gluten-content flour you will be using (there are plenty of Google results for any flour). Don't be afraid to make a mix to get what you want.
Some flours will require more flour / less hydration to achieve the appropriate dough characteristics. You can research this, but time and trial are eventually going to be your guide so that you can tell by touch and look whether or not it is accurately mixed.

In dealing with Gluten in flour; for the purposes of food sensitivity, you can't diminish the gluten content by any technique. If it's there, then it's not going to be viewed by most people on a GF diet, and certainly much less anyone with Celiac's, as palatable. Here are some trouble-shooting points to consider with respect to navigating gluten;


Kneading creates the network of gluten strands, this helps the bread stand up on its own (exploratorium has video on this). Also, salt and yeast fermentation help to develop strand development.
The purpose of giving your dough a rest after kneading is to allow the strands of gluten (the bonds mentioned earlier, these strands are what hold the dough together) to return to their  relaxed shape. If you are experiencing snap back (esp. problematic when shaping a dough for a pizza shell) either the dough needs a rest, the gluten content is too high, or you could use a dough relaxer.
Shorter fermenting, higher hydration, high fat (fat inhibits gluten formation), and lower-gluten content make for less elastic doughs. They will break apart rather than stretch. If this is problematic, introduce a flour that has a higher gluten content to the mix. 
A good example of a dough that should not have a high gluten-strand formation would be pie crust. To inhibit gluten formation, and get a rocking crust, you should use small amounts of water, not knead very much, ice all of your ingredients somewhat, and use shortening; these things all inhibit gluten formation and give you that drift away crumb texture. Additionally, crumbly biscuits using unscalded milk are benefit from an enzyme that inhibits gluten formation (incidentally, scalding the milk inhibits the inhibitor)