It depends upon the range that they can read minds. If it is fairly close range it will be of limited use. If someone gets into close contact with them and is a better fighter or has a firearm mind reading won't help much. Even if the person knows what is coming they still have to be able to stop it.
That would be interesting but easy to defeat. Granted they would know you are there to stop them but unless they have an escape plan then it could be over for them. My mind is so messed up I will be thinking of something like the little mermaid as I was shooting them.
Someone who knew what you were up to would be able to stop it because you would probably indirectly think about the way to stop it as well. The range is important. If they have unlimited range then that would be tough, maybe it would have to be a coordinated effort so thinking about different minds all at once would be hard to track.
It doesn't matter if they know how to stop it etc. Knowing every punch or kick that my opponent will utilize against me means nothing if they physically outmatch me. You might know what a professional boxer is going to do next against you but your odds of having enough skill to actually put that knowledge to good use is slim to none. Of course if the mind reader has fairly equivalent physical skills then the mind reading would make a huge difference.
I agree with the importance of distance. If someone could read minds at great distances then they have a decided advantage… but they have to be reading your mind. There are literally billions of minds out there to read… how would this mind reader know to be focused on you? And Kyrroeth is correct about abilities. It makes little difference if Jet Li is in front of you about to kick the left side of your head in and you know he's going to do it. Chance are you don't have the physical prowess to stop him. Now, if it is more of a mind control power, like Professor Xavier, that is a different thing altogether.