The home of a night full of stars, lake of water lilies, and lady who doesn’t smile. What am I?

I am a word of letters three; add two and fewer there will be. What word am I?

A salt often found on a countertop. In certain settings, don't let it drop.

I open paths you can’t go through. I turn but only you will move. When you lay thee down to sleep, protection through the night, I’ll keep. Lest you forget to use me right, someone may wake you with a fright.

Sounds like a physician, But more of a no-tail condition.