[Mithadan]

An excellent analysis. As I lack any real background in medieval miltary tactics and strategy, I cannot contest your breakdowns of the respective military forces, but I will offer some comments based upon what we know from LoTR.

There is no direct evidence the Beornings used cavalry. Beorn himself appears to have travelled to the Battle of Five Armies on foot. While they are of the same stock as the Rohirrim, this alone is not a basis to conclude they preferred to battle on horseback. Rather Beorn seems to be based upon the berserker.

I doubt that the Elves of Mirkwood carried spears in any great number, at least when defending their own land which is heavy primeval forest. The use of guerilla-style hit and run tactics using bows and knives is more likely. Compare them to the Green-Elves of Ossiriand, who, for example, waylaid and destroyed a force of heavily armed Dwarves using such tactics. Legolas, presumably arrayed in anticipation of the likelihood of combat, carried only a long knife and a bow. If he preferred or was used to carrying heavier weaponry, he certainly could have been so armed by Elrond.