Your math is reallly bad...
1 clam = 0.00645 BTC not 0.012 BTC...
Sorry about that.
At the time we had two banners paying 1 CLAM per day each and one banner paying 2 CLAMs per day.
I couldn't decide whether to say people were paying 1 CLAM or 2 CLAMs per day - it looks like I said "1 CLAM" but converted "2 CLAMs" into BTC, so got a number around twice the actual price being paid.
There's two ad spots. For both, it would be .012
No, there's a single funding pool. Each spot's content is picked randomly based on how funded each ad is. It's possible to pay just 1 CLAM per day and get your ad shown in both spots if you're lucky. Or if you ad is the only one that is currently funded.
Typing "/ad list" in the Just-Dice chat tab will show how much each ad is paying per day at the moment.