okay,your post is kinda confusing.
1) gaara can make sand clones of his own which can not only disperse into sand,but regenerate from damage,and he can make more clones than itachi can. Gaara would just let his own clnes deal with thse of itachi's.
2) dont know what you are sayin abt mizukage and muu,but gaara sensed them easily,muu himself acknowledged it and gaara found the clam through mizukage's genjutsu and showed onoki where it was,so him sensng the clones,which itachi can make like 2 or maybe 3 would not be difficult especially when he has several of his own clones around.
3) gaara dosent have to worry aby blocking that sword,his sand blocked one when he wasnt looking,and i am sure he can bring his sand to protect him in time if he managed to react to a rising forest.
4) shushi's eye only works for his own ms,and it is a bloody crow,can a crow bypass gaara's sand?