G'day Ozziecheese,
I'm making Cams again today also. I'm using the traditional recipe from carol Wilman's book Home Cheesemaking. It uses a meso starter culture, and I use liquid rennet. You have asked me about brining before.....I can say that your brine time looks way too long. I brine mine in 25% brine for around 1 hour for a 250g cheese.
Critical to making cams, IMHO, is the amount of stirring after cutting and the length of time before moulding. too much stirring and the curd gets too dry (this can be adjusted by cutting a little larger), too little and the cheese will be too moist.
Draining time is also critical, and is best done at higher temps 25 - 30C), good now that summer is approaching. Some recvipes I have seen suggest draining for up to 48 hours. yuo need to get the PH down and the moisture out before maturing. If not, the cheese will be very soft (sounds like you have seen this before) and will ripen VERY quickly, getting ammoniated and liquid under the rind.
Anyway, have to go now and add my starter, good luck!