Michael, welcome to the forum. BluErf makes some very good suggestions. The more good keris you look at, the easier it will be to tell the bad ones. I tend to agree on the issue of fakes. A keris, IMO, can be deemed a fake only if it is being presented to you as something it is not (i.e. a newly made keris being sold as 17th, 18th, 19th Century). Please remember, high quality keris are still being made, it is a living art form. A few quick points:
1. If someone is offering you a "gold" keris naga for less than many (MANY) thousands of dollars, it is not an authentic old piece. Even at the source in Jawa, high quality old pieces sell at a premium. If it's too cheap, there is probably a reason. Gold keris naga or even keris naga w/o gold adornment were NEVER commonplace in old times.
2. A keris without a seperate gonjo is NOT a basic sign of a new OR poorly made keris. Though old Gonjo Iras (one piece) keris are rare they do exist. I have a rather nice early 19thC one in my own collection. Though probably made this way to save the original buyer a little money, they have now become very collectable due to their scarcity.
3. I don't know if the blades you show are yours, but for the most part their quality appears fairly low. The keris singo in the first pic might have some age and be fairly decent, but i wouldn't be able to tell you from the provided picture. For some reason, someone stuck a Javanese mendak on the Bugis keris on the left in the second pic. If this keris is yours i would remove it as it doesn't belong on this keris. The keris naga in the third photo looks like it might have been a later addition on an older blade. It appears to be poorly carved and there are signs it is not original to the blade.
4. Here is the short list of some books you might get to help you in your appreciation of keris:
a) "The World of the Javanese Keris", Garrett and Bronwen Solyom
b) "The Kris", Edward Frey (get the 3rd Ed.; more photos)
c) "Kris the Invincible", Vanna e Mario Ghiringhelli (small, but brillant photos)
d) "The Kris-an Earthly Approach to a Cosmic Symbol", David van Duuren
e) "De Kris - Magic Relic of Old Indonesia - Vol. I, II, and III", G,J.F.J. Tammens
As i say, this is the short list of books written in English, but since living in Indonesia you probably know the language, you should find even more available to you.
You also might find this web site of interest:
http://www.nikhef.nl/~tonvr/keris/