Whether robots should have rights or not I think depends on exactly how advanced they become. Present day robots, definitely not. But perhaps in the future, if machine learning perhaps starts showing signs of sentience, then maybe.
Every worker being replaced by a machine wouldn't work in a capitalist society, but would in a socialist/communist one. So yes, I think it is fine - it would give people the freedom to do what they want with their lives, rather than have to stress over being able to afford food and a home.
Upgrading bodies past natural limitations does already happen to a certain degree with caffiene, steroids, and other drugs. Any modifications that significantly improve quality of life should be available to everyone, otherwise you'll end up with a top 1% of elite superhumans.
There have been some interesting TED Talks about the future of AI: