To what extent are you allowed to modify secondary attacks? Some secondary attacks require you to spend a target lock, or a focus, etc. But there are a few that don't require you to spend anything.

On a secondary attack, how are you allowed to modify the attack dice roll?

Take into account:

-outmaneuver

-range

-target locks

-focus tokens

What are you allowed to apply and modify on secondary attack rolls?

The only thing that cannot be used to modify Secondary attacks that can be used to modify Primary attacks are the Range modifiers.

Yep. You don't get the bonus die at Range 1, and the opponent doesn't get the bonus die at Range 3. Everything else is kosher.

First off a quick definition.

A secondary weapon is any upgrade card that has the Attack: Header

The condition for outmaneuver is "when attacking" - so it applies to all attacks - primary and secondary

Range bonuses are not given for secondary weapon attacks - neither attack bonuses nor defense bonuses (core rules page 10)

Target locks are usually spent to fire missiles and torpedoes (so you don't get the benefit of the reroll)- exceptions are the Proton Rocket which requires you to have a Focus token - but does not require you to spend it to perform the attack (so you can use it to modify the attack)- and the Homing Missile which requires you to have a Target Lock but does not require you to spend it to make the attack (so you can use it to modify the attack)

Cannon weapons and turret weapons (upgrades with the turret icon - NOT native turrets on ships like the Falcon, Decimator, and YT2400) are also secondary weapons - most do not require a focus or target lock as a condition to fire them - and will allow you to use those tokens to modify the result.

The exception is the Blaster Turret which has the "Attack:Target Focus" header and requires you to spend the focus to make the attack.

Focus tokens may be spent as normal - note that with proton torps which allow you to change 1 focus into a critical result, you may use a focus token to change any additional focus results into hits