Mithril questions

[Madak]

1. A normal breastplate has an armor check penalty of -4.

Does a mithral breastplate have an armor check penalty of 0?

Armor check penalty decreased by 3 for the mithral property and decreased by 1 for the masterwork property?

2. You can cast spells while using a light shield. If you have a mithral heavy shield, can you cast spells while wielding it because it is treated as a light shield "for purposes of movement and other limitations" (from the PRD)?

[Quantum Steve]

1. Mithral items are always masterwork,the -3 to ACP includes the masterwork bonus

2. Only Armor is counted as a category lighter.

[Carbon D. Metric]

1: No, it would have a ACP of -1. The masterwork bonus is included in the description. All mithral armor is considered masterwork.

2: Not 100% sure.

[Ravingdork]

Quantum Steve wrote:

1. Mithral items are always masterwork,the -3 to ACP includes the masterwork bonus

2. Only Armor is counted as a category lighter.

This.

[Madak]

Thanks!