geegee said:

Actually, what I have read, is that when Israel would fail at keeping the Laws, there was some adjustments which made it even easier for them? I don't know how true that is, but, this seems logical (?)

I don't think I ever heard any such 'adjustments' to make following the law easier.

...to the point where God says that He even has to make a NEW covenant with them which was NOT after the manner of the fathers when He brought them out of slavery.

If you look, the new covenant was to be a reiteration of the former Law,

"But this shall be the covenant that I will make with the house of Israel; after those days, saith the Lord, I will put my law in their inward parts, and write it in their hearts, and will be their God, and they shall be my people. And they shall no more teach every man his neighbor, saying, Know the Lord, for they shall all know me...for I will forgive their iniquity, and I will remember their sin no more."

The new covenant has not occurred yet, and verse 34 does not refer to a "second coming."
                In addition, the Christian approach to Jeremiah 31 rests upon one premise, and that premise must be examined. The premise is that a "bris," a covenant, would include a new set of laws. However, if you look   throughout the Old Testament, you will find that "bris" does not mean a set of laws, but rather, a creation of a bond, a creation of a closer relationship. Thus, the Christian interpretation, which justifies a new set of laws (Christians do not keep kosher, observe the Sabbath or Yom Kippur, etc.), is built on a false premise in the first place. See Genesis 9:12; God is not commanding the animals; He is creating a relationship with them. See Genesis 15:18; there is no set of laws being commanded or changed. See Deut. 7:2; do not create a close relationship. See Jeremiah himself, in 22:9 -- because they broke their close relationship with God and worshipped other gods instead. If it meant, because they broke the laws, then why specify that they also worshipped other gods? It would be as if one would say that not only did you murder, but you also robbed! Look at these verses and you will see that a "bris" -- a covenant, never refers to a set of laws, and so the missionaries are really using this verse by mistake.

What is interesting to me, at this point, is how Israel, or certian authorities, have the power to decide who the Messiah will be?

The way I read it, we ALL will be able to decide who the messiah is; it'll be obvious by reason of the fulfilled prophecies.
But, the messianic prophecies were given to the Jews, and to no other people. They were charged by God with keeping them. It only makes sense that God would make absolutely sure they understood what it was they were waiting for.

And all or most have been fulfilled.

Care to give specifics? I don't see any fulfillments of any of the pertinent prophecies.

It is just that some want to set their own table and set their own requirements, etc, and have power over God's own words. Let me ask you, nojc, is there one scripture in the Hebrew writings that foretell of a 2000 year (and still counting) dispora of Isreal? I haven't found any, perhaps you might have?  
 
I don't know if there is any prophecy that gives a specific 2000 year time period.
I do know there is no prophecy that says that the messiah will come and then die, and that 2000 years will pass before he returns to finish what he started. Do you know of one?