Welcome to the wonderful world of Scotting and to the board!
As far as I know there is no other book that the Book of the Scott. For all other things a search in Technicalities is always a good option. I think was too small to be of interest to Haynes..
Concerning the rad… you do not state if you want to use the bike in winter or store it. In the first case I always use normal antifreeze for cars. Seems to work nice and keeps the water nice and clear. If you want to store the bike you could do the same or simply drain the entitre system. Just not forget to fill it up again in spring…