Attacking over Rivers.... is it actually relevant

[oagersnap]

Maybe if ranged units attacked from higher ground (like bowmen, musketeers, riflemen, rader artillary, etc) then they should get an attack bonuse because they're shooting down, not up. I've noticed that ranged units don't move from their square when they attack, they just stand there and shoot. But if there are hand to hand combat units that have to go up to the enemy units to fight then they should not get the bonus because they have to cross into the enemy square to fight.
And what does SOD stand for?

I don't know wether ranged (I mean like archers, not artillery) units do also have a smaller chance of winning when they attack over a river, but it would be very realistic if there was no defence bonus in that case. But when ranged units attack, they will move close to the defender if it's a "normal" unit, and stay where they are if the defender is ranged too.

About the mountains, I usually attack from there. I also sometimes bring some defensive units too, sometimes the AI will kill a lot of enemy units because of the 100% defence bonus and the fact, that the enemy will usually bring all of it's offensive units against them, no matter how many times they lose, or how much weaker their offensive units are than my units' defence.

About SoDs, it is mostly better to attack from grassland, since SoDs are usually tanks/MA with 3 movement points, so moving over a mountain will cause the units to end their turn immediately, so you have to wait one more turn to attack.
The exception here is when you attack a city with 20+ (or something like that, depending on the size and strength of your SoD) defensive units. In that case, there is a chance that you won't capture the city in the first turn, and when the AI has so many defensive units, it will probably also have lots of offensive units nearby to destroy you.