For me the book I have had the most fun with for supplementing the fantasy menagerie in the core rule book is Creatures, Critters, and Denizens by Jeff Rhodes-Gloor.
http://www.lulu.com/us/en/shop/jeff-rho ... 34809.html The amount of detail, creativity and illustration that went into this book makes it well worth owning.
In that same vein of wonder there is Goodman Games' own, 'Random Esoteric Creature Generator' by James Edward Raggi IV right after you read this you should check out the link and buy it.
http://www.goodman-games.com/4375preview.html You'll never think about monsters the same way again.
In regards to the rest of your question, I'm aware that the same desginer who brought us the Creatures, Critters, and Denizens, is also working on a new book called the Liber Arcanum which looks to be very exploratory in the realms of magic. Here is Jeff's most recent description of the contents;
Amongst other things, the book contains :
* 2 expanded and fully illustrated rune sets (Mortal and Fey) as well as some new uses for runes.
* Blank rune art so you can make your own rune sets.
* an expansion on the 5 element theory introduced in the CCD, which includes maps of a celestial geometry of the 5-element system as well as randomized table s for plane hopping. (color versions of these maps and an excerpt from Liber Arcanum on this subject are available at my 10/19/13 blog post on
http://myaereth.blogspot.com/ )
* 6 patrons; based on the general concepts of battle, exploration, and the 4 basic elements
* Appendix I. This is a short tag-on that contains: a magic weapon record sheet, 9 new powers of types 1 to 3, 6 new banes and bane creatures, and the rules to support an expand version of table 8-1 of the Sword Magic section of the core rules to include all melee weapons as well as ranged weapons and ammunition. It also contains 40 pre-generated magic weapons set up in randomized tables by power:
twenty +1 weapons, eight +2 weapons, seven +3 weapons, and five +4 weapons for those occasions when the players find treasure you didn't see or wasn't defined in the module write up
* several new critters and supporting equipment
* This book will hopefully be up on the EBM printing network, so folks in other countries can have a hard-copy printed on demand so as to avoid international shipping rates and much, more...

Found on this thread:
Here.
And that's about as much as I can recommend for now. Nothing special comes to mind for sources on extra equipment, but thankfully of all the things your asking about, equipment is the easiest to adapt from similar fantasy role playing games, or just create from nothing. I hope that helps.