no
Yes, like almost anything else.
If you don't get up for days at a time, yes, because you can develop bed sores. update: mentioned above is the LEAST of your worries! The average amount of sleep an adult should have is 7 hours...
A lot of juices are quite high in fructose, which is a form of sugar found in fruit. Too much sugar is unhealthy, even if it is fructose.
Too much of anything is bad. That's why it is called "TOO MUCH".