OK well for starters you don't need any higher pressure for the silicone than you need for the resin, since during casting the silicone will only be compressed tot he resin pressure anyway. That said, even for resin the higher the better.
Here's a good number for you: 28.3. To convert CFM to litres per minute just multiply the number by 28.3
The CFM of the compressor isn't all that important as you want a compressor with an air storage tank. The transfer rate between the tank and your pressure pot will be much higher. For the compressor you will want a tank size of at least double that of your pressure pot.
The compressor and pot you linked to are far, far overpriced! The compressor should be just a cheap one from an auto or hardware store, no more than 120 euros. The pressure pot should be a similar price (eBay?).
Here in Oz we are Metric too, but unfortunately many measurements involving pressure and air are still imperial. You just have to get used to it
Oh yeah I can make that....