RE: If I'm immortal, I don't need to know
"We" have the potential for immortality in the realm of planitary time. The important part in the above sentence is "we".
Humans are so locked up in their illusionary ego that they cannot conceive, by and large, that they are a small part of a greater whole.
The greatest bait and switch in ego history has to be the reincarnation story. Here we have a practise that councils that ego is a myth and offers techniques to quell its power over the practisioner only to add as an afterthought, 'Oh yeah and the same ego is born into other sentient life forms indefinitely'.
If one believes in evolution and sees that a life form exists (at least on this planet for sure) which procreates and reshapes into many forms, just as a tree puts out different branches, then we may say for certainty the we are immortal.
If there is anything close to being immortal, that would be the proton and the tiny bit of consciousness carried with it. Scientists have done some math and found that if man has freewill, then so too does the matter of which he is composed.
A little higher up, as you allude, then it's the DNA. That is our "reincarnation". Our sole purpose, as far as I can see, is so that DNA can replication. And it is entirely possible that DNA is conscious.
This is a concept never before visited by me yet fascinating all the same!