Does the shooting require skill or is it target and press button?
There is skill involved. If you are a light tank especially, and pretty much any tank, you want to stay transversal to other tanks. (side to side) as it's harder to be tracked by the turret and there is more of a spread in the aiming.
There is an 'auto-aim' mode (right click on a highlighted enemy tank), which can be used to help guide your aim at tanks but it's not entirely accurate. It will try to keep the turret aimed at the tank and show you where to lead in order to hit it. The fact that most tanks stay moving doesn't lead to the best accuracy. It's point and shoot if they aren't moving though, but those people just suck.
But the question is, do you fire at the enemy sitting still but you have a wider cone of fire, or do you wait a few seconds for the aiming to 'zero in' thus increasing your chances of hitting the enemy, but knowing that they may move which will screw everything up?
Also, your crew helps accuracy, load times, etc. There are actually two reticles. One is the actual gun, the other is the cone of fire. Different guns have different aiming delays, these can be sped up with a better crew.
As your tank crew gets better (more games played) you become more accurate, load your gun faster, spot enemies better, etc...
There are systems that can be damaged. If you aim at the tracks of another tank, you can immobilize them.
*If you hit their turret, it can be immobilized, even the gun itself can be damaged and that will result in reduced targeting ability (bigger spread of fire)
*The engine can be damaged which results in slower speed or immobilization as well. Fuel tanks can also be damaged, not sure what effect this has though.
*Radio can be damaged which results in you not being able to communicate enemy positions on screen to your team.
*The ammo rack can be damaged, this can result in loss of ammo, or even detonation which will blow your tank up.
*The tank can catch on fire and it slowly loses health until your crew puts it out.
*Crew can even be injured which results in everything from more spread, slower loading, less radio, etc.
The crew will fix all these problems, unless it's critical damage, a better trained crew fixes the problems faster.