In PvP, how does Unstable Affliction affect the healers, strategically?

Question

When playing in large PvP environments (rated battlegrounds, primarily), healers have the responsibility of dispelling their teammates. Warlocks have the responsibility of using Unstable Affliction on as many players as possible. The description of Unstable Affliction states that "if the Unstable Affliction is dispelled it will cause 2007 damage to the dispeller and silence them for 4 sec."

Does this silence suffer from diminishing returns (first silence is 4 seconds, second is 2 seconds, 3 is 1 second, then immunity for 15 seconds)?

What happens when a healer's Mass Dispel dispels multiple UAs? Do those suffer from diminishing returns (e.g. a healer that dispels 4 UAs at once is immediately immune to the silence)?

How do healers deal with the silence? Can other healers dispel the silence?

Please note that I am a DPS player that has never played a healer before, so bear with me.

Answer 1

Does this silence suffer from diminishing returns

No. A player who dispels Unstable Affliction will get silenced for four seconds, every time. Here you'll find a list of buffs, debuffs and their diminishing returns updated to 4.3. Notice that the silence debuff you get from Unstable Affliction is nowhere to be found.

What happens when a healer's Mass Dispel dispels multiple UAs? Do those suffer from diminishing returns?

The healer will be affected by a single silence debuff, which does not have any diminishing returns.

How do healers deal with the silence? Can other healers dispel the silence?

There are a few ways in which a healer can deal with Unstable Affliction:

Priests have Inner Focus if they chose the Strength of Soul talent

Paladins have Aura Mastery or Divine Shield

Shamans can use Grounding Totem to catch an Unstable Affliction being casted by the warlock, if they can time it right.

Druid is the only healing class that lacks Silence prevention.

However, any player can use the PVP Medallion in it's various iterations, to remove the silence debuff. Alternatively, humans may use their Every Man For Himself talent to achieve the same result.

This silence effect can be dispeled by another player, too.