At eight weeks I'm guessing she is a lot more resilient to change than you may guess. With the swaddling, if she is wriggling out of the blanket, then she needs a better blanket. If she just cries and resists emphatically, well then swaddling is not her thing, for sure. I also don't think it is a huge deal to let her sleep on her tummy. If there are no other factors that could lead to SIDS (blankets, pillows, second hand smoke, etc.)then I say go for it. Lots of babies aren't capable of sleeping through the night without waking until they are closer to 6-9 months, so expect her to go through spells of night waking.
My thoughts are a little disjointed here but I guess I am saying, keep trying to help her learn to self soothe (try different pacifiers, blankets - www.miracleblanket.com - or music), place her crib or co-sleeper in a close locale, let her lie on her tummy if that works for you and expect her to have some occasional night waking spells since she is still so small. I agree that she is too little for CIO but another fabulous sleep book is Healthy Sleep Habits, Happy Baby by Dr. Marc Weissbluth. He details sleep patterns and issues by age and is a great guidebook.