It looks like a funny thing happened on the way to the forum...
Regarding Zen Buddhism and Taoism being alike, not in my experience. Yes Taoism influenced the evolution of Buddhism in east Asia and vice versa, but to suggest the two are similar is imo outlandish. (and regards the OP about whether Buddhism is all sugar and spice, I don't have a quote handy, but there are plenty of examples of Chinese Buddhists talking trash about Taoists in the literature; there was no love lost there.)
As noted, Buddhism is a large umbrella including interpretations which are hardly compatible under the same word. I'm also told by a former Buddhist living in Korea that it's easy to misunderstand the beliefs if you rely upon English translation of technical terms like dukkha. I come upon this all the time with people attempting to understand the notions of emptiness and the middle path based on what the English words suggest to them.
That preface out of the way, a book I'm reading (Doubt: A History by Jennifer M. Hecht) suggests that the Buddha's original teachings were largely agnostic on the questions of reincarnation and karma, and that these notions were incorporated as Buddhism evolved out of the background of Hindu culture in the Indus Valley. (I've also recently been clued to the possibility that the evolution of Buddhism at the time was also strongly influenced by political realities of the time, but haven't followed up.) Indeed, there are even Buddhisms that lack the metaphysical component.
I have a few loose wires in my brain, the result of which, sometimes, religion takes on a dire importance for a few weeks and then goes back to normal. Thus, I've flirted with Buddhism, and during these episodes, I've even converted to Buddhism, so I know a little, but not a lot. To my mind, Buddhism simply doesn't make any sense without the metaphysical doctrines of karma and reincarnation. And I can't believe such things. (My recent reading also inclines me to believe there are more fundamental disagreements between myself and the Buddha.)
Beyond that, there is the question as to whether Buddhist psychologies and practices are useful in and of themselves, independent of the metaphysics, as a sort of technology. I found studying The Transmission Of The Lamp very useful, and have used Buddhist concepts to understand puzzles in my Taoism, but that may simply be the nature of the two systems, compatible, if not necessarily true. Apparently there are Buddhists who would answer in the affirmative, but I suspect they are the Buddhist equivalent of Deists and Agnostics, needing to distance themselves from the primary beliefs but unable to completely let go.
Anyway, enough rambling.