I would most definitely put a piece of paper towel in the little plastic baggie because condensation does tend to occur inside. I don't now what people put in the brown envelopes (I just read somewhere that they use them because they had them lying around). The plastic baggies would more than likely be cheaper and easier to get.
Yes they can sit until next spring or this winter. Most people just keep them in the fridge until ready to plant. I have heard someone say (can't remember where) that they just put them in the envelopes (might be same person as above) and stored them in a closet where it was cool (this is called dry storage) and they were just fine when they planted them.
Oh by the way, I mailed your seeds today
