08 KX250F front brake rotor loose and front brake loss.

I just bought a 08 KX250F and i noticed that the front petal rotor is wobbly and movable. It doesn't look like the rings on it are tighten-able. Is the front rotor some type of desgin or something that makes it better? But here's a problem I think I know the answer to. If I'm walking the bike and I pull in the front brake slowly while i'm pushing it, the lever goes all the way in without any effect on the wheel ie no braking. If I let go and then squeeze in then it's back to normal. But it kind of scares me because it happens when I'm riding and I have to let it out and then pull it in fast. I've been told by two different people that I probably need to bleed the front brakes. Also, in the brake fluid res. on my right hand side of the handlebars, I don't see any fluid inside it. Do I just add fluid or is there possibly some kind of other problem? Thanks to all for taking the time to read this and hopefully shedding some light on the said issues.