Camfield
First this is literally an introduction and I'm sure that the questions you have are legitimate and easily answered if asked.
The point is that mass combat, even skirmish, is different. Units do have facing, flanks and rears, and the issue is not that a small unit has a problem changing face, but the fact that it actually has one and has to appropriately protect its flank. Besides, most small units are actually skirmish units and do not have to worry about facing.
The retalitory attack comes from a doubling of actions to speed up the game. It is also an attempt to avoid rolling inititiative for each individual unit, which is the alternative to the completely unrealistic my whole army moves and attacks, your turn. Rules provide for first strike where models with reach, or great initiative or attack the rear of the unit can strike without retaliation.
The combat resolution is fast, exceedingly fast. In game we see upwards of 15 turns a side in 2 hours, after a short time reviewing the rules. Ask any table top gamer and they'll tell you that is fast. Hell, we've had 3e party combats take longer than that. However, I can see that there would be concern over the modifiers, but can only stress these are light, structured into intuitive clusters and easy to apply.
Re tables - I still hold that if the rolepaly simulation has tables, and mass combat system based on it also will necessarily have tables. Besides, the intent is not to post the whole system (96 pages) on the board anyway.