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So, is the number being tested for being prime or not? What is the "64bit LucasLehmer residue"? Would we know whether or not the number was prime after 7 days? When do we come to know whether or not the number is prime?

By doing the LucasLehmer test, you are testing whether the number is prime or not. It will not give a factor, just tell you whether it is prime or not. If it has a "residue" (what is left over after the test) it is not prime, if the residue is 0, then the number is prime. I am going to assume that the "days to go" is 7. In that case, in 7 days, you will know what the residue is. If there is no residue, the number that you are testing is prime.
As for why your P90 CPU hrs/day is so low, this i can't explain. Maybe one of the moderators or someone more knowledgable than me will be able to answer this one for you.