Don't expect your campaign to look the same one week or two weeks after initial setup. The initial set up is a jumping point only. The real work comes later in analyzing the data, adding new keywords and evolving the campaign into something profitable.
If you are not flexible or are not comfortable with change, ppc will be quite the challenge for you. A good campaign will ebb and flow and change LOTS!
The good news is that this is where a SMB can thrive. You are more nimble and do not have to go through all the red tape and bureaucracy that a corporation usually does to get even the smallest changes approved.
Also, let your agency be your expert!