Ok I am going to qualify my position a little bit
Question 1 Information
MIE mentions both Wikipedia and the Pony Club Manual . Both of these have descriptions of use and fitting of most nosebands . I also have a copy of Saddlery by Elwyn Hartly Edwards which also has uses and fitting.
A recent UK published magazine called Horse & Rider had an article on nosebands. I know that if you type in nosebands in wikipedia it will give you the most common nosebands and from that you can search Cavesson, Flash, Drop ,Grakle and Kineton ( the most common nosebands ) in this forum you will find hundreds of threads which discuss nosebands. So ALL of the information anybody could possibly want is avialiable.
Question 2 Availability and ease of access - Wikipedia , google , forums , books , trainers , other horse people are all available, easy to talk to and in most cases free advice is there for the asking
Question 3 Where to find out the information.
As previously stated if you type in Nosebands in Wikipedia it will list the most common nosebands, most saddlery , tack, training manuals will have a section on nosebands which is in the index of the book. You could walk upto most trainers and other horse people and talk about nosebands.
As I said before - the information is there, it is easy to get hold of and if you have an ounce of intelligence is easy to understand. Some people today just seem to be lazy and want to be baby-fed everything.
When I first started riding in 1984 things were different as I was limited to books, magazines and local people, but today I can ( this forum is a perfect example ) talk about almost anything with enlightened people from all over the planet - all I have to do is ask - and read.