Question #1: Does general grievous lose any power from the cw to rots?
Nope. If anything, he should be deadlier for the experience. His performance was similar to Hypori when he captured the chancellor, killing a few jedi. Of course, the theory has been put forth that Grievous owes much of his "prowess" to his exotic nature and the element of terror and/or surprise. To say his chest was crushed and he's somehow weaker for it is nonsense. His body is artificial as it is.
Or would obi whoop him crushed chest or not?
Actually, looking at the fight, Obi-Wan had the upper hand when they fought with lightsabers but I wouldn't say he whupped him. Grievous was surprisingly cocky and unaccustomed to Obi-Wan's style and he made a lot of errors that got him prematurely owned. Notice that after losing his hands he starts playing ti smart and retreats. After that he fights very unfairly.
Question #2: Is count dooku better than sidious?
As a force user? Debateable. Dooku only uses the Force for a whopping eight minutes or so in AOTC, while Sidious uses the Force for an entire epic battle in ROTS, showing feats like tossing multiple pods, etc. It seems like Sidious is the more powerful Force user, but the difference from say, Sidious to Dooku is pretty small compared to say, Sidious to Obi-Wan.
In lightsaber duelling Dooku is clearly better. In form, execution, and speed he bests Sidious.
And is sidious a good ligthsaber duelist?
Well, he has speed, but otherwise his skills are lacking. Despite what NG promised us, Sidious' style is... horrid. His clumsy stabs and awkward thrusts only make him look foolish and even his confirmed lightsaber kills were just nonsense in execution. He can contend with Yoda and Mace, but not for very long it seems. Obi-Wan or Anakin could possibly overcome in lightsaber combat but Sidious' control of the Force and lack of personal honor would prevent such a victory.
Question #3: Where does darth maul fall in the power scale?
Depends, really. He's below ROTS Anakin and Obi-Wan, since both would destroy him with their speed and precision. He could probably take Grievous. Asaajj? I say it goes either way. Asaaj is a battle prodigy. Since Darth Maul displays little in the ways of the Force visibly, I'll rank him based on perceived lightsaber ability:
1- Dooku/Yoda
2- Mace
3- Anakin
4- Obi-Wan/Sidious
5- Maul
But that's just a rough generalization, not exactly accurate to a point.
Question #4: Mace vs sidious who wins?
Well, Sidious was cocky and was never able to kill Mace nor use the Force or terrain to his advantage. It would depend on the location. In that office Mace had the edge, but in the senatorial room Sidious would defeat Mace.
and mace vs dooku who wins?
Dooku. Mace doesn't display the offensive (Or really any) Force powers to contend with Dooku and while his style is comparable with Dooku's, it does lack the precision and efficiency of the Count's style.