General Shadowrun Questions III: Ya like that, Chummer?

[Lord Torath]

2E Availability:

For this Acquisition test, the gamemaster rolls a number of dice equal to either the source's relevant Special Skill (such as the fixer's "Equipment Acquisition" Skill) or the standard Etiquette Skill (Street, Corporate, and so on), adding +2, against the first value of the Availability Code, which serves as the target number.

Does the +2 increase the dice rolled for the Etiquette Skill, or to all searches?
Do you use the PC's Etiquette skills, or the source's Etiquette skill?
If it's the source's Etiquette skill, is there any way to spend karma to increase your contact's Etiquette or Special Skills to make it easier to find rare equipment?