Questions about random character movement and hit detection for game [renamed]

Hey every one i was thinking of making a new game where there are rebel smiley men( because i love smileys) and you just kill them and get as high a score as you can.

What i need to know is how i can make them have random movement.
Not just normal random movment but when it decides to walk up it will change to a different frame within the rebel and make it face the direction of its movment.

i also ened to know if when a mc moves into a invisable barrier or the rebels sight that it will try and kill the mc.

Thanks in advance