FF, I don't know if Buddhism believes in the Jesus story or not. Buddha predates Jesus by about 300 years, and by thousands of miles, as Buddha was born in India. Maybe even the same soul.
Yes! I believe in reincarnation, assention to the spirit plane as a master teacher (sort of like a Saint) no longer requiring "earth time", and further assention to heaven. The spirit plane and heaven being different things. These fall into more Buddhism teachings of enlightenment.
Yes, the Jesus story is told over and over again in other cultures, cultures that had no contact with Christianity nor the Roman Empire which post-jesus carried the "message" of Christianity throughout, as did his many followers. My own "belief" without proof is that Jesus existed, but The Christ exists. Unfortunately, Paul really did a whack job on Jesus work. Do I believe the bible? No. Do I believe parts of the bible? Yes. There is no whole book or cannon of books that does not carry mans' (or woman's) attitudes and influences.
Yet there are incredible pearls. I put Paul down, but his section on Love to the Corinthians, especially as broken down by Rev. Henry Drummond in "The Greatest Thing In The World" http://website.lineone.net/~henrydrummond/greatest.htm is incredible.
When god-entity (I am an agnostic also, because I do not believe god-entity is a diety to be glorified) said "let there be light" The Christ being is the one who threw the switch that started the Big Bang that put Evolution in motion. Yes, I believe in Intelligent Design with no christian or other religious influences.
Agnosticism leaves the mind open for any and all, or no thought on god. This one I learned here and took for my own here on JWD.
Who else has The Christ been on earth? I don't know. Maybe he did, indeed, reincarnate here on the Americas and select 12 more apostles as the Mormons teach. Maybe he was Buddha, Krishna, Ghandi. Maybe even Pope John Paul II (who I believe is another peacefilled soul ascending the ladder toward heaven, not The Christ).
Mary, too, is found in many cultures. I believe one of her older "incarnations" is Kuan Yin, who predates Buddha by several hundred years.
What have I studied, who's writings. Hard for me to define as I catch bits and pieces here and there. Most of my study is experience, human and ascended master teachers. I've had the privledge of meeting many along my journey.