Thanks for sharing. What is your definition of eternal life and is there anything that can separate you from the love of God?
My definition of eternal life is Christ's definition of eternal life:
John 17:3
"And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent."
Eternal life is found in knowing God and Christ, and this "knowing" is not just some sort of mental assent or acknowledgement of their existence. If it were, then even the demons would be saved because they believe in God in that manner (James 2:19-20). Instead, this "knowing" speaks of an intimate relationship between two parties, as in a man and his wife "knowing" each other intimately, or where the two become one. In the case of the Christian and Christ, this oneness must be a oneness in spirit.
1 Corinthians 6:17
"But he that is joined unto the Lord is one spirit."
If we were to continue on reading Christ's prayer as is recorded in the 17th chapter of the gospel of John, then we would see that this is the type of oneness that he was praying about, and, again, to answer your initial question, this is how I would define eternal life.
Which leads me back to my earlier question to you.
If, in the case of Christ and the Christian, this oneness ceases to exist, then do you not see how the relationship is broken?
As to your second question, which is derived from what Paul said in Romans chapter 8, if you keep on reading that same epistle, then you will find your answer.
Romans 11:16-22
"For if the firstfruit be holy, the lump is also holy: and if the root be holy, so are the branches. And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree; Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee. Thou wilt say then, The branches were broken off, that I might be graffed in. Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: For if God spared not the natural branches, take heed lest he also spare not thee. Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off."
The same Apostle Paul, to whose words you alluded in your second question, went on to say that if we do not continue in God's goodness, then we shall be cut off.
Now, what do you suppose that means?
We both know what it means, and it has nothing to do with eternal security in the way that some people here are presenting it.