Finch requires MCC access to run an Audit report.

Finch can link to a client’s AdWords account by asking the client for their AdWords Customer ID number. We then submit an invitation to the client asking for permission to link to their account.
http://support.google.com/adwords/agency/bin/answer.py?hl=en&answer=7732

Each direct AdWords account can be linked to up to 5 MCCs, so there should normally be room for Finch.
http://adwords.blogspot.com/2011/06/new-my-client-center-feature-provides.html

Occasionally Finch invites the top MCC of a client. It is only possible to have one MCC link to a top account (i.e. another MCC account).

It is not technically possible for a client to invite Finch to access and manage their account.

Yes. For example, if you use Webtrends, Omniture, or Speedtrap, you need to install Google Conversion Tracking since Finch uses this to track performance This also provides you with a vendor independent data set for your paid search campaigns for future needs.  For instructions on how to insert this, please visit adwords.google.com/support/aw/bin/answer.py?hl=en&answer=115794

It depends on the complexity of the campaigns, but on average, clients go live within 2 business days after the audit is accepted, the subscription agreement is accepted, and the payment information is entered.

Usually you see a significant impact or shift within two weeks after the live date. More than 90% of clients see a significant impact within the first month.