Custom-Made Judaism?

This post is in response to some issues I received via private email.
The basic issue concerns whether there is any common core of teachings uniquely Jewish, given all of the branches and offshoots from those branches. A related issue is that given the many different interpretations of just about everything, it seems as if each individual is free to define and practice Judaism however they want.
First of all, my book addresses these kinds of issues throughout, and there is a specific section in the Appendix on the Movements/Branches of Judaism. So, I would refer everyone to my book and particularly that section in the Appendix, and I will not extensively repeat that material in this response. My short summary and finding is that there is a certain common core of observances, such as the general set of holidays, reading the same Torah portion and Haftorah on the same Saturday, that are observed in some form or fashion, and there is a certain common moral code (in the realm addressing relating with ones’ fellow human beings). There appear to be bigger differences in the realm of how one is to address one’s relationship/attitude/approach towards God, and attendant sets of rituals, dogmas, doctrines and beliefs.
I have often found in my studies of both contemporary and historical Jewish thinkers, particularly the ones that are more mystically-oriented, that one can read several pages and realize that what is written could have been written by a mystic of any number of varying traditions. It is only at some point when the author makes reference to a Jewish term or source, that the writing becomes identifiable as Jewish. There are efforts being made by various contemporary movements, such as Rabbi Laible Wolfe, Chabad, Jewish Renewal, etc. attempting to reframe Judaism in terms similar to Eastern traditions, in attempts to attract people of Jewish birth to reconsider Jewish sources; that meditation, mysticism, chanting, concepts of the divine impersonal, reincarnation, etc. also exist in Judaism, and somehow may be better than any others and more suited to people of Jewish birth. I have not been convinced by the claims that the Jewish versions are somehow distinct from or better than versions found in other traditions. And I am not convinced about claims that engaging in mantra practice in other languages, such as Sanskrit, is somehow harmful to Jewish souls, or the related dogma propagated by some that there is a distinct "Jewish soul" or "godly soul" only possessed by people of Jewish birth that is damaged by engaging in practices from other traditions. I also do not subscribe to the claim that chanting Sanskrit mantras is invoking Hindu deities, and thus is a form of idol worship.
However, I do recognize that Judaism and Yoga are two of our most ancient spiritual systems upon which others have been based, and I believe that both Biblical Hebrew and Sanskrit are Sacred languages of equal potency. It also appears that the "remnant" of people of Jewish birth currently living are disproportionately represented within the realms of spiritual teachers in many varying traditions, particularly mystical and meditation-based traditions. I believe this relates to the "light among the nations" concept, but that true spiritual leadership begins with humble service, not with arrogant boasting and claims to some kind of exclusive spiritual superiority.
As far as custom-tailoring one’s spiritual and religious practices and observances, I think that has always been done to some extent, as all laws and dictates are always subject to interpretation and individualization to some degree. While many traditions emphasize the importance of communal worhip, ultimately one’s relationship with God is an intimate, private and personal matter. There are warnings from various sectors against do-it-yourself approaches, some understandable, some not. The real danger is that if everyone is free to follow their different drummer, and claim divine guidance in doing so, this can result in conflict on many levels. It seems like much of the religious strife that currently exists and historically has occurred, leading to wars and oppression of all types, are always justified by different sides claiming that they have the exclusive inside access, and anyone else who differs is mistaken and must be converted or destroyed. This is another theme and issue addressed in my book, so I will go no further with it here.
It appears that the solution to the above problem is that there are certain lasting moral codes that have been generated throughout the centuries that provide some universal guidance, although always still subject to possible conflicting interpretations and applications. Judaism has provided the Noachide Laws (and the Ten Commandments and Ethics of the Fathers), Yoga has provided the Yamas and Niyamas, Buddhism has provided the Eightfold Path. Many traditions have provided variations on the Golden Rule. My spiritual father, Swami Rama, often stated the following simple formula: "Perform your actions skillfully, selflessly, and lovingly."
Enough said for now.