1. I think its perfectly fine that if you choose to extend your life you also choose to undergo sterilisation. If the state offers this facility, it might put some additional conditions on it - terms of military/community service. There will also be some heavy taxes paid on your wealth and/or a reduced rate of interest.

2. Living till the end of the universe would mean reconstructing your body/brain millions of times. I don't truly see any way around that. There can be 'gaps' of thousands of years between such reconstruction depending on the current resources of human civilisation.

3. It's perfectly acceptable to have both old and new humans in the mix. Natural selection isn't the only factor driving evolution and besides by your logic everyone suffering from medical conditions should be allowed to perish so that only 'fitter' humans reign.

4. The wonder of knowing what human civilisation is like thousands or millions of years from now. Learning hundreds of professions - each to mastery and the limit of human knowledge. An unbroken chain of human history. The ability to gain advice from your ancestors and lend advice to your descendants.

5. Yes, life extension should be a choice. By law, no one should force this on anyone. But again, no one should be forced against it either.