M.C.
Sleep - does he have a night light or a table lamp? We had to put dreamcatchers in my kids rooms. They seem to have helped. Maybe he could go to Build A Bear and make a Nighttime Buddy, dressed in Ninja clothes that will give him strength?
Seperation Anxiety - this is a real feeling, but for most kids is the oldest trick in the book.He's in first grade, so he will know the school, some of the kids. Our school has a meet and greet a few days before school starts so that the kids can meet the teacher, see some other kids, pick out their seat, drop of supplies, etc. Treat school like he's going to a job. It is his job and he doesn't have a choice. When talking to him about school, make statements that are matter of fact.
Instead of asking - 'Do you think you'll make friends today?', say 'Try to say hi to one new person today.
Instead of 'Hope you like your teacher.', say 'go easy on your teacher today'.
Instead of 'Hope you have a good day', say 'Can't wait to hear a fun thing about your day.'
Power struggle. All kids do this. Just decide what you are willing to accept, and what you aren't and be consistent. When my kids get bossy, I just look at them and say 'um. No. Try again' and then I wait for them to reask their request in a nicer way. Being consistent is the key because once you let something go one time, that will be the way it is.
Good luck
M.