Manipulating names and abilities for heroes

i was wondering if i could change some things like names and abilities for the heroes by tweeking with the mod files. is this possible?

i want to change powers, and performance abilities like speed, power, ect. let me know of any such changes if possible and of any other related changes that might me interesting
im pretty sure that by tweeking with the notepad files for the heroes, i can make some changes, but i dont know how.