So, I've seen here and there people say that there's going to be rules that mitigate some of the shooting damage and that flank/rear charges will have significant effects. Does anyone have more details about this?

I think not. It will be soon though. I guess we will know when FFG posts the combat preview.

I think what we have heard through the demo so far is:

1. Flanking and rear charges add a yet unknown number of panic tokens.

2. The damage dice gained through formation will be adjusted in some way if you are flanked or rear attacked (presumably lost).

3. Shooting damage will be mitigated by the range template in some unknown fashion.

A lot of people have been talking about how powerful the reanimates ranged attacks are, but remember that the demos we have watched, the models were either set up in or moved directly into the range of the archers. Once folks understand the ranges and mechanics, you will most likely be able to avoid/mitigate damage via good deployment and movement. Note that the archers cannot move and attack, nor can they charge (which makes sense), so the gameplay around archers will likely be to treat them as a threat zone where only good trading units enter their zone.

For example, assuming they can fire at a range of 4 out of 5, approximately 8 inches (we are not sure if this is the case, but 5 is the maximum that the range template permits and I assume things like siege engines would be higher than bows). That a unit of spearmen can advance 3 and defend, advance 3 and defend again, then charge with 2 with higher initiative...each of the two volleys they have to eat will be at +2 armor with a 16 model unit. If the archers try to move to avoid, they cant attack. If they stand and shoot, then the spearmen can close the gap. Once they charge, the spearmen will crush the archers, even if they lose half of their models getting there. The point cost is 32 archers to 30 spearmen, so it would be a win for the spearmen.

The point isn't that this is exactly how it would play out, but seeing relatively squishy fast moving Calvary charge blindly into an arrow volley and watching the damages isn't the best indicator of power. Even if the Calvary does just rush the archers, but defends on the way, that changes them to a 3/1 with a 4 movement. They could reach the archers in 2 turns, eating one volley.

Archers are range 1 to 5, not 4. Advance 3, +1 armor is init 5, if the archers attack before that the +1 armor doesn't matter. I don't have screen shots of the archer dial to compare them to to say for sure. Even if they move first, a 2x2 of archers will probably do 6 to 8 damage. More with blight.

Edit for correct numbers on Archer damage

Yep. Means two trays of archers in melee with two trays of spear men. Who wins? Spearmen do and remove a 32 point unit with a 30 point unit with having some left over models to still do work. What is the issue? Seems balanced.