Go to "Advanced(in the tool bar) >"Gameplay constants" there you can change a lot of stuff (mostly values, here you set how much experince hero gains, how much life does each strenght point gives, etc)
For icons go to "Advanced(in the tool bar)>"Game interface" there you can change the icons and texts( like hero armor icon is an helm, you can change it to some armor and change the text for it)
And welcome to the Hive, rihmakala!