1) Is Google Base dependant on Adwords?

I had Google Base up and running last week and, while I got very poor impressions and clicks, I was getting a few and I could see some of the items. Tonight my Adwords balance ran out and I cant find anything in Google Base leading me to believe you need Adwords to have anything showing up in Base but am I wrong? Maybe Google favours advertisers over non-advertisers?

2) Is there any logic to how Google Base displays results?

For example, I would list a fictional item as follows:

ABC123 Little Red Car by Ford £19.99

On my site it would just be listed as Little Red Car with the model number and manufacturer in the product description.

By my reckoning, that should cover most bases of what my customers search for - the model number, name and manufacturer but still I get very poor impressions.

I assume like Google itself the actual logic and algorythms etc are secret but is there a trick to getting things to display? Is my logic of how I display items correct or not? All my items are set to published and searachable so I guess I was expecting more traffic than Im getting!