Welcome to the Q&A Forum

I would use target CPA. This option gives AdWords more flexibility to generate conversions and it tries to keep the average CPA over a longer period below your target CPA. As target CPA you put a price that you are happy to pay for a conversion. (Don't lower the recommended bid too much)

Since your campaign's main goal is to drive conversions, I would choose the 'optimise for conversions'  Ad rotation option. After a while you can remove ads that have a low converison rate and add new ones, based on your best performing ads.

Good luck!

I'd also say that's the most logical explanation. On your 'Campaign Overview' page you can check 'Last Linkscape index update' to see if this differs from the date displayed in Open Site Explorer.

I think the point is that the Goal Conversion Rate shows the percentage of the TOTAL visitors on your site that convert. The Abandonment rate shows the percentage of visitors that leave the funnel before completion. I don't know how you've set up your site and the funnel, but I think that some visitors might enter the site on a page that is not included in the funnel. When they leave again, they will count as a visitor, but not as a funnel abandonment.