Interesting, so I don't mind if movement can not take back if there are hud info like, chance of hit(not including unrevealed/hidden enemy), facing attack bonus(if action points still allows following attack), line of sight indicator(ie if an enemy is blocked they will covered in a different color).
Or, let us take back movement only as suggested, and player can check line of sight with out other info.
For 2. my reason is, current system only show you how much for certain action cost(bright green) on the dot bar. If you have too few dots left, extra ones needed will turn red. Essentially like the movement cancel part, it's for game flow wise. If you have to constantly checking how much these 3 spells cost and casting range, back and forth checking how far you can go so remaining points can let you attack and with in range, it's gonna be a PITA. In some regular fight it's okay, heros can tank it, but on bigger fight, as in game play video they did during KS campaign. People frequently misclick and committed move already, and left with no enough action point to do anything else.
Implementation wise I don't really care, just a clear gauge that shows how your movement is going to affect your attack-ability. Say, if you move too far, specific spell icon will have a dynamic 'X' mark overlay on it, that's also good to me. There needs to be a clear indication for multiple action point system like ours. In XCOM you have 2 points only, so it doesn't really matter.
For change facing after movement, I think it's kinda needed, otherwise people will resort to walk L shapes to get the facing they want, which is also 2 step. Attack will automatically face your character to mob, that's fine. But when you want to reach mob fast and tanking, you might run to a bad situation without things like, run to a corner and facing out, run to 2 adjacent enemies and facing stronger foe, or just simply run ahead without blocking your ally's line of sight but in current system it might leave your back/side open for attack.
About flee exploit, that I didn't think about.
![laugh laugh](/images/graemlins/default_dark/laugh.gif)
But there could also be a balance to do.
1. If you flee, you have to run away far enough, that's already done.
2. If you enter battle, you should automatically be last in queue.
So you can't enter and heal right away.
3. Re-engage distance should be the same as flee distance, so even if you buy potion back, you have to run toward your dying ally, with that last in queue penalty.
4. There could be map edge/entrance that's exploitable even in this case, if this is the case( spawn with in engage distance), you are automatically disabled 2 turns, and still last in queue in turn 3.( roughly based on what current system is doing flee, you have to run two turns straight to get enough distance to flee )
So penalty wise to get extra potion is pretty heavy in this situation, you have to spend 2 turns out of engage distance, go buy potion while your ally wait(to exploit TB system), and come back you have to wait another 2 turns at least to heal your ally. And, if mob have some buff when one of the player flee, like buff moral, chance to hit, that would also be interesting.