not sure what coupon you are talking about specifically...usually people will write down where and when they found/got the coupon
Yes. Usually if you were going to trade with someone you would message them and set up a trade (i.e. ask for what you would like and make an offer from their wishlist, etc), usually both parties would agree on what is fair. Then you would exchange addresses and mail them to each other, using a private message. You can see how many trades someone has made by looking at their "trade rating" which is underneath their name on their posts. People get this number by having people "rate" the trade after each trade (you can choose positive/neutral/negative) and also write a short message about it (i.e. fast trader, generous trader, etc).
Yes post responses are just kept in the thread, you won't get a message in your inbox to let you know- you just check back in on the thread. If you have a specific question for a specific member, that you want to make sure you don't have to look for the answer, you could always send a private message.
There is a "new the SC thread" here http://forum.smartcanucks.ca/179335-...s-read-canada/ which might help answer some of your questions. If it's not in there feel free to send me a PM, I'm not a expert but I can do my best to help you, that way we're not cluttering up this thread which is suppose to be for coupon scans and reference.
cheers