Pikoro,
1. around what time period the sling was invented
The sling was developed as early as 10,000 B.C. (Korfmann,
1973; Ferrill, 1985; Grunfeld, 1996). The oldest recovered sling dates back to around 1323 B.C.
(Tut's sling)
http://www.ashmol.ox.ac.uk/perl/gi-ca-qmakesumm.pl?sid=149.169.152.78-1094669253... 2. more information on the amount of damage a sling stone can cause.
Blunt force trauma; broken bones. Penetration of flesh was possible.
Vegetius, a Roman writer in the late 4th century, observed in
his famous Epitoma Rei Militaris:
Soldiers, despite their defensive armor, are often
more aggravated by the round stones from the sling
than by all the arrows of the enemy. Stones kill
without mangling the body, and the contusion is
mortal without loss of blood.
Celsus, a Roman medical writer from the 1st
century B.C.. He describes in his De Medicina
that:
...there is a third type of [projectile] that sometimes
needs to be removed, a leaden bullet or rock or
something similar, which breaking through the skin
lodges inside in one piece. In all of these cases, the
wound needs to be opened a bit wider, and what is
inside must be extracted with pincers along the same
pathway by which it entered.
3. its accuracy and range compared to that of the bow
Accuracy in trained hands was superior or equal in my opinion.
Livy’s History of Rome, which was
completed in 9 A.D., he states,
A hundred slingers were recruited from Aegium
and Patrae and Dymae. These peoples were
trained from boyhood [...] Having been trained
to shoot through rings of moderate
circumference from long distances, they would
wound not merely the heads of their enemies but
any part aimed.
Can you get some range data of the ranges page here on the site:
http://slinging.org/ranges.html