Pretty much I want to echo this. Being a submissive does not mean the person you're with shouldn't listen to you, what you want, what you aren't ok with. If someone takes advantage and abuses the power you're giving them, you can take it back and end the relationship with that person.
Oh dear that seems like a loaded question, lol. The good qualities are going to vary based on who you ask. For some it might be about letting go of the control, or not feeling responsible for what's done under your Doms control, for some it might be about feeling safe and/or cared for, or maybe they just feel good when they are being told what to do and/or dominated. There's no right answer. The important thing is figuring out what you like and knowing that it's ok. If you're a sub, great! If you're not, that's great, too.
Figure out what makes you happy, find someone who can give that to you. Don't let anyone tell you what you're feeling, or what you should be feeling. The best advice that was given to me was: It doesn't matter what you think you should feel, it only matters what you DO feel. Trust your instincts.