Your bag must weigh no more than 70 lbs (but hey, please don't stuff it just because you're allowed 70lbs!) and hold your clothing for 7 days, your sleeping bag and your pad (thermarest or air mattress). You COULD tie your sleeping bag to the outside of your bag, but with a bag this big you won't need to.
This particular bag is the Rolling Adventure Duffle from LL Bean. In Extra Large, it is $99.50 so be sure that you are planning to use it a few more times to make it worth your while.
Packing: Start looking for 2 gallon ziploc bags. I use 1 bag for each day of cycling clothing- my shorts, jersey, sport bra, socks and bandana. At the end of each day, my stinky clothes go into the ziploc bag, and my clothes for the next day go into my sleeping bag so that my body heat can keep the clothes warm for the next morning, when I have to put them on before daybreak. At the end of the week, the ziploc bags all get emptied directly into my washing machine (eeeeuuuuww!)
Wondering about more? Stay tuned, or drop me an email to ask me!