OGRE - Animation time? Realtime character control

I am interested in learning a 3d engine THinking of Cinema4d. with this in mind I looked for ways to implement my future designs into max ; I found jit,ogre's animation, it is very interesting.

My question is with regards the animation time, whenever I load the Jit.OGRe examples and hit the behaviour animation presets, they usually last a very short time and loop.
Is there a limit to how long you can make the mesh/armature animation loop. Say if I want an animation of 5 minutes so that a user could affect the animation differently during the five minutes. IS this recommended , possible?

or is it better to use counters to control small loops and make the characters be actually dynamic?

when I tell the ninja to attack he attacks in a loop, if I add a walk it is a walk attack kind of loop.. how can I make him walk and stop and attack punsh,,... resume walking stop and the jump resume walking stop and the fall. etc

thanks for the help - THe max community is the best.