Did you read your 2nd link? All of the typically bad sides in the second grouping are related to poor hygiene and needle sharing. The first grouping is more benign than most antidepressant sides.
Yes, I did. Nowhere does it say that. If you want to get a point of reference for what heroin might look like if it wasn't a street drug, oxycodone is quite similar yet distributed without the additives found on the street since it is manufactured by big pharma. Still, it is associated with respiratory depression.
I know it doesn't say that but it should be obvious most of them are due to poor IV administration. You don't need to administer heroin or morphine via IV.
True, people occasionally OD on prescription medication, but it's usually as a rebound after having the prescription withdrawn and then finding more drugs.