b) Co-sleeping is dangerous, full stop, especially for neonates/infants. If you manage to avoid smothering your infant by accident, then that's awesome, because I'm sure it is better for bonding. But the risks are way too great. Maybe if the baby is 9 months+, but even then....no way. Maybe a bed extender or something so you can be close without risk of smothering, but the risk or suffocating the child is way too great if you can just roll over on them.
That is total and utter bullshit. The fact of the matter is that you have to be pretty much drunk off your ass or otherwise seriously inebriated to smother an infant in your bed. And no, parents who are sleep deprived aren't usually seriously inebriated. I know that the plural of anecdote isn't data, but at the same time the only smothering deaths I've ever read about were due to extenuating circumstances. I've raised five children and I can tell you, sleep deprived or not, if there's something making me uncomfortable in bed I'm gonna move, and I'm a very sound sleeper. We usually kept the infant in a crib next to the bed for easier breastfeeding, but all the infants slept in the bed with us on multiple occasions.
As far as data goes... the Canadian Paediatric Society states that "Bedsharing with an adult who is extremely fatigued or impaired by alcohol or drugs (legal or illegal) that impair arousal can be hazardous to the infant." which is pretty much what I said above. The Public Health Agency of Canada recommends room-sharing and states that there is an increased risk of SIDS due to the baby suffocating due to several factors (soft mattress/pillows, becoming trapped in the sheets, and also due to rollover of an adult). It does, however go on to say that the risk is higher if the adult is drunk/stoned. It specifically mentions not using co-sleeping products (not sure what those are). Wikipedia states that "Bed-sharing is known to be dangerous for any child when a parent smokes, or has a history of skin infections, but there are other risk factors as well." It goes on to list the same risks that the other two sources give.
So no, Co-sleeping is not dangerous, full stop, whatever. It's perhaps not the safest thing, but it's also not considerably more dangerous either.