hero/bl on arenas and cc/silence questions

Hi, 2 days ago I was playing arenas with friend and several times we met shammys who used heroism/bloodlust.
We thought that on arenas people cant use cooldowns like hero, is it a bug or it's normal ? What skills with big cd we can use on arenas ?

Second question: Does the duration of cc (polymorph, fear etc) is decreasing every time its used on the same target ?

I'm playing discipline priest, and I have talent "unbreakuble will", that reduces the duration of stun, fear and silence effects done to me by additional 30% and I got meta gem that reducing silence time.
so third question: Is this talent working ? After mages counterspell I cant use my holy spells 8 seconds, after hunters silencing shoot I cant use my spells 3 seconds.

1. Not a bug.

2. It's called Diminishing Returns

3. Talent is working. Don't let a mage interrupt your spell with counterspell or it locks out that school of magic for 8 seconds.