That would be relevant if you had to actually find each other in the forest. That’s not the case, so it isn’t about familiarity, but distance. The distances in combat are short and would not take much time to traverse. The same applies to the ability of the unit’s to quickly engage each other in combat, as I described above. They might not always want to, but they can if they so choose. This is different from a game that has the assumption of larger distances as there you cannot engage each other quickly, even when you want to (Rome Total War). As for the time spent on the battle itself, that just seems long because it’s turn based rather than real-time. The events taking place of which the turn-based system is an abstraction, actually happen much more quickly in this case.
Because units within range of the battle already take part right now. This means that for reinforcements during the course of the battle to be implemented, you’d need to make it possible for units farther away to join the fight. For those units to ever join, turns need to take a relatively large amount of time, otherwise they will never show up. You’d also always have to act fast as the entire map is effectively enemy territory.
The enemy bases already sent out groups depending on whether they think they can take you, they just don’t leave the base unattended (to my knowledge).
A time consuming battle is already resource intensive in that you have to replace everything used and lost, plus that you already expend further resources through moving around, recovering, buying, etcetera on the world map. Having the amount of time you spent on the battle itself have an effect on this is an unnecessary punishment that does not facilitate interesting gaemplay
Because the time suggested by the combat itself would not reflected by the passage of time, as I have outlined above.
Fatigue already reflects this so you don’t have to change anything if you want to see that kind of dynamic. Adding incremental fatigue increase however, would result in it eventually becoming impossible to act, since a unit’s recovery would eventually be unable to keep up with the cost of actions. This will happen much sooner to a low fatigue character, giving high fatigue characters a game breaking advantage on top of all the advantages that it already offers. As for the undead, most of them do not tire, so unless you’d manage to kill them all in a few turns it’ll become next to impossible for you to beat them.
Spear and dagger? What are you talking about?