Your mind can't keep a dream going without visual so you will probably wake up.
It generally isn't a good idea to close your eyes, but you can keep the dream going as long as your other senses are being used. In one of my recent lucids I couldn't go through a door I wanted to walk through, so I closed my eyes and floated right through it just fine and opened my eyes on the other side still in the dream.
As far as control goes I think its just a matter of practice. Try different methods to do what you want. I tried using a door to make someone appear and it didn't work so then I tried walking to my neighbors house to find them and they were there. Also if you fail to do something don't let it get to you. Lately I've been unable to fly also, which is weird because in my first lucids the only way I got around was flying. In my last lucid I couldn't even walk straight I was stumbling around like a drunken idiot for a good chunk of the dream. But I just dealt with it, laughed at it, and I regained my balance later after I forgot that I had been stumbling. If you get disappointed and start thinking you'll never have the control you want then it will only get worse. Just enjoy all of your successes and don't let your failures phase your determination.