If the conditions match two signatures, do they both get triggered or only the first one?
You can only filter on those things. You can however create a custom signature that matches on something in the payload and then create a filter that subtracts all actions and has a "stop on match". If the signature matches every packet, then this should work quite well (we do it in fact). If the signature matches only one packet of many [in a stream you want to guarantee no alarms for] I'm not sure that it will work.