Use internal contractors to contact and do initial screening of candidates. Then it moves directly to the hiring manager to will typically do a phone screen. Once your past the phone screen will be brought internal for interviews with Engineering, Marketing, Sales and management executive. They will each focus on a specific skills, knowledge or behaviors.
They typically like to bring in about 3-5 candidates for a role before a decision is made on any of the people. Some roles will fill in about 1-2 months from start to finish while others have stretched out to more like 3 months before a final hiring decision is made.