When you join the Banner-Ex banner exchange, you will be presented with a screen which allows you to upload a banner from your computer. Press this button and you will be able to select an image from your computer. Once you have selected the correct image, click upload and your banner will be shown to you. Your banner impressions and click thru statistics are available to you online 24 hours a day. In to your members area, and your real time stats are shown to you.
Bannerad rotation is random and dependent on site visits.
If a banner appears on a page a banner impression would be generated. Yes, the parameters you select when determining your web site targeting help to determine what banners will appear on your site. Other advertisers will be targeting your audience.