Ok so we finished making our characters today. I'm an Iron Hands tech marine. My power armor history is:

Bring Death from Afar: While wearing this armour, the wearer never suffers any penalties for moving and firing with a pistol- or basic-class weapon on semi- or fully automatic fire (see pages 239 and 242). Additionally, the wearer may count any heavy weapon he wields as a basic weapon for the purposes of moving and firing on semi- or fully-automatic fire.

So I've got a decent ballistic skill and thought, hey why not try grabbing a heavy bolter and doing so work. Which means I could do this:

Full Auto Burst:

Normally Semi/Full-Auto Bursts do not allow Movement unless using Pistol or Basic weapons only.
Normally Semi/Full-Auto Bursts with Pistol/Basic weapons incure penalties to the normal attack action.

Normally Semi/Full-Auto Bursts require the use of a Full action.

Normally Heavy weapons require Bracing to fire without penalty.

Bring Death From Afar nullifies the normal penalty for moving while using a Semi-Auto Burst (Technically a -10, bringing the +10 of Semi-Auto Burst down to 0) or Full-Auto Burst (ignores the -30 from +20) but only when using actual Pistol or Basic weapons.

Example: Firing a Full-Auto Burst and with a Bolter while walking your AB in meters would normally give a -10 to hit, with Bring Death From Afar the character can fire with the normal +20 to hit while walking his AB in meters.

Bring Death From Afar allows the character to treat a Heavy weapon as a Basic weapon for the purpose of moving while firing. The Heavy weapon is not a Basic weapon naturally so the full penalty for using this option is still in effect (-10 to hit), it simply allows you to use the move option available to a Basic weapon. This effect provides no other benefit for Heavy weapons, so technically if the marine did not have Bulging Biceps (but he does) he would still need to brace the weapon before firing it.

Auto-Stabilized makes a Heavy weapon always count as braced. Additionally the operator of such a weapon may fire a Semi-Auto or Full-Auto Burst as a Half Action instead of a Full Action. Deathwatch Suspensors provide an additional benefit, removing the penalty for moving while firing a Semi or Full-Auto Burst.

Bring Death From Afar allows Heavy Weapons to move and fire with Semi/Full (with normal penalties as a Basic weapon). Does not grant bracing or faster actions.
Auto-Stabilized always counts the weapon as braced and makes Semi/Full-Auto Bursts Half Actions. Does not affect movement while using Semi/Full-Auto.
Deathwtch Suspensors grant Auto-Stabilized as above, and also allows movement while firing at no penalty.

Example: A character with Bring Death From Afar and Auto-Stabilized could fire a Semi/Full-Auto Bursts while moving with normal penalties as a Half Action (You may only use 1 movement subtype action each turn).
Example: A character with Deathwatch Suspensors could fire a Semi/Full-Auto Burst while moving without any penalties as a Half Action.

Example: A character with Bring Death From Afar could fire a Semi/Full-Auto Burst while moving with normal penalties as a Full Action.

Finally, counting all universal talents available to all space marines the bonuses the following traits/abilities grant a character with the Bring Death From Afar ability which are not granted by Bring Death From Afar are:

Auto-stabalized: turns Full Action Semi/Full-Auto Bursts into Half Actions
Deathwatch Stabilizers: As Auto-stabalized, removes penalty for moving while firing.

Bonus question. For future reference when I get my servo harness, what talents would i have to get to blast away with a storm bolter or heavy bolter AND shoot my flamer or plasma pistol mechadrite

Two Weapon Wielder (Ranged)

Be sure to read up on Two Weapon Fighting on page 246.

Although, you will still recieve a -10 penalty to ALL shooting, both main-hand and off-hand/mechandrite, when using Two Weapon Fighting even with said Talent. (Assuming Two Weapon Wielder and Ambidextrous talents.)

you sir are a gentleman and a scholar. Thank you for your in depth response.