Regarding movement speed, do you mean how many tiles they can move in 1 turn?
Regarding ranges, I personally would like to see some sort of range penalty to encourage units to get in closer. I'm just not sure how much impact we want to have this have or whether it's worth doing if it's not going to have a significant impact.
In game design we have a couple of key questions we have to ask ourselves
- Does the mechanic have a material affect on game play?
- Does the mechanic reinforce other mechanics?
- Can the mechanic be clearly communicated to the player?
- Is the mechanic compatible with the rest of the gameplay?
If the answer to any of these questions is no, then it becomes suspect.
Re material effects on gameplay: If the suggested mechanic doesn't really have much impact, then it's basically just noise. There are lots of strategy games that give the illusion of depth because they are full of mechanics that don't really matter. We had this problem a lot in War of Magic where we had tons and tons of little stats for units that ultimately didn't matter (piercing damage vs blunt damage for example which made no real difference).
In Sorcerer King, we do have Cold, Poison, and Fire damage because we are making it so that entire factions have this kind of damage and thus if you end p having to go against them, you'll want to prepare for that. Once we balance the minor factions, hopefully these differentiations will matter a lot more.
This is why I don't like terrain bonuses. Unless terrain matters a lot, then it's going to make players feel like they have to micro manage every battle because obviously the AI will never play nearly as well as the human and auto-resolving battles will never be very good.
Re reinforcement of mechanics: We used to have a concept of unit morale. The idea being that the attacker's morale would go down every round of combat and morale affected all the stats of players. This was an interesting mechanic but was kind of a dangling mechanic that was also very powerful. Morale didn't come up anywhere else in the game except battles so we ultimately took it out.
In Sorcerer King, we've tried to tie everything around a handful of mechanics: Doomsday counter, Magic, Crafting.
Re Communicating it to the player: This is, by far, the most common issue that people ignore when suggesting new game mechanics. If something can't be communicated to the player then it becomes frustrating.
Flanking is a really good example. What should constitute flanking? When a unit has to turn around? When a unit moves X tiles from behind to hit a unit from behind? What's ironic is flanking is a lot tougher idea to implement than say backstab. I think backstabbing would be a lot more fun because then you have to time your attack to when a unit isn't facing you.
RE Compatible with the rest of the gameplay: This is another common issue that comes up with people suggest gameplay features. If you asked certain enthusiast GalCiv players what they'd like to see in GalCiv III they would say that the invasions should be practically a separate game. That ship combat should be basically a separate game. That planet building would effectively be a game unto itself. And so on.
Ultimately, a game can't be all things to all people. Someone who likes Space Empires V may not like GalCiv because they'd consider GalCiv too "shallow". Someone who really likes Dominions might not like Sorcerer King for the same reason.
Sorcerer King's tactical battles aren't supposed to be particularly sophisticated. But they are supposed to be more sophisticated that FE/LH. They aren't there yet. That is why we like talking to you guy -- because this way we can get other ideas.
Hopefully those of you reading this lengthy comment might have a better understanding of the decision making process we go through. 
Cheers
