Default Samsung galaxy ace(gt-s5839i)

Because mobile is not mine and belongs to a person who would not know lot about mobiles e.t.c. i want a simple program which possible(maybe like this) you can do just move(or even safe full uninstall without cause any problems at the mobile/system) the system app on the memory card to release some of tiny internal memory of the mobile has and whenever the internal memory fills the cell begins slow down in everything even at scroll contacts .

What do you suggest I do on mobile so as to simply forget these issues?
I know how to make it rooted by that file from recovery menu. Is that correct?