That's normal. Interrupt lasts 3 rounds if not cleansed.

Edit: Only if it is Acupuncture like Neji Skill. This post was last edited by man***@gmail.com at 2016-9-1 07:35 This post was last edited by man***@gmail.com at 2016-9-1 07:45 This post was last edited by man***@gmail.com at 2016-9-1 07:46

They probably outspeed you, because they have more initiative (a value in the game which determines 1st movement) or are just positioned on a position before your character e.g. 1st and your character is on 2nd position within your team setup.

As to the rasengan cooldown, it seems as this is intended and normal. I just checked the informations provided within the skill and it says after 2 times use, there will be 4 rounds of cooldown.
So if you channel it and you get interrupted it will count as used, but you're not able to use it a 2nd time as you're in a state of debuff as it is with acupuncture - Lightning character afflicts acupuncture too.

As a small tip which I use often, I can only recommend either using your skill later in the round after they did their skill and if you got acupuncture on you either use a healer which will cleanse it or just wait it out.

I hope this helped you.