Mona has had a few books published over the years that delve in to her method. Any one of these can be used to arm a parent/teacher with the skills to easily teach a child to read. Unfortunately there are restrictive publisher copyrights on these that make the reproduction of them problematic. Reproducing her books on this site with text extracts is not going to happen until these hurdles can be overcome.
Fortunately however a solution presented itself while constructing this site - video lessons !
Sometime around 1992 Mona made a video version of Step By Step to which she holds the copyright. Its existence was something I was completely unaware of. Split in to an introduction with 16 lessons the video is essentially a moving image version of Step by Step. It gives a unique insight in to her phonics programme with Mona as the principal presenter and teacher. Wishing to have her work preserved for future generations we hit upon the idea of sharing the videos on the Internet Archive site. Each video is released with a Creative Commons Licence that allows and other interested parties to share and redistribute. The timing of this was significant for the site as there are slight variations in her published on which book to align the sites content to was proving tricky as I wanted a user to easily jump between any of Mona's published work and the DVDs present a very unique solution to the problem. We therefore hit upon the idea of taking each video lesson and building the sites content and pages around each one.
The joists as described are not up for bearing weight. Not sure of the code requirements in your area but it sounds as if you have a hand framed as opposed to trussed roof. Even so, it sounds as if the 48" on center joists are not to modern code. Is there a central beam that the joists tie into? I would guess there must be since we're talking only 2x6es.
1. If there is a central beam so that the joists only span 12 feet, then getting 2x6 on 24" centers would support storage in my opinion, but your local inspector may be of a different mind. 24 feet is a long span for a 2x6, so without a central beam I would be hesitant to put much weight up there. I don't have my span table on me but that would be a good place to start for maximum span as a function of spacing and lumber.
2. The new joists in the middle between studs should not be a problem if you have a double top plate which is one of the main reasons a double top plate is required, if not it should still be OK for storage. Again your local inspector would be the end authority. You could put joists on 16" centers over each stud to be safe. This would only be 6 extra joists, so not much money. Tougher to get big stuff into the "attic" though.