RPG actionscript

1

2 questions…

  1. What is the actionscript for:
    if key “down” is down, switch symbol to walk down,
    if key “up” is down, switch symbol to walk up,
    if key “left” is down, switch symbol to walk left,
    if key “right” is down, switch symbol to walk right,

and

  1. How do I make a battle system? E.G. placing HP, AT, DF, SP, EVA, ACC and MP (also for the enemy) and show them, also making the functions, EG:

When enemy attacks(“root_hero HP” == “root_hero HP” - ((“root_enemy AT”*2-“root_hero DF”))

Hope this made sense