Good question but a difficult one to answer.

In WW2 the Germans and Allies both used some sort of APCBC (Armor Piercing Composite Ballistic Cap) at the later stages of the war. The Russians was abit late to adopt this high quality ammunition.

Before this APC and APHE were common munition types. Anything that is solid metal of one type is a "shot" anything that contains explosives, other metals or materials is a "shell"

APCBC works by having softer metal coating a harder and stiffer penetrating core. This would allow the shell to "grab on" to the enemy armor preventing deformation witch could absorb penetrating power. The softer outer metal layer also held the shell together and prevented it from shattering on impact.

After an AP shell/shot penetrates the main damage will come from hot or cold metal fragments like shrapnel from the shell or spall (shrapnel from the tanks armor). This could wound or kill crew aswell as ignite the munitions.

The germans used gasoline engines aswell as the american M4 Sherman, the reason the M4 had a reputation of burning is because the lack or protection for the stored ammunition. The german tanks had armored internal compartments to prevent a munition fire.

Countrary to popular belief a HEAT round does not utilize the thermal energy (heat) to penetrate the armor of a tank. At the point of impact a copper cone lining high explosives will be accelerated and punched forward at a speed of 7-10km/s (about 17896 miles per hour or 28800 km per hour). This causes the armor to often fail and be penetrated. Once this happens it is hell inside the tank.

Primary damage will be to the crew since the immence and sudden pressure changes will cause multiple organ rupture and almost instant death. The crew itself might look unharmed (except dead and not moving) with no external wounds but they are messed up and broken inside. The pressure also has a possibility to ignite the munition stowage.

Secondary damage comes from the molten copper residue that is injected into the tank, igniting fuel, cloathing and ammunition.

Anyways, back to the matter at hand. Crew position casualties!

I must admit that i have no idea what is fact or myth but according to sherman tank gunner Kent Tout he claims that he aims for the enemy gunner if possible to prevent the enemy from firing back at him.

The standard procedure in shermans was to bail out if you heard something smack against the armor. The crew knew their tanks was inferior.

If you want me to expand on anything or have further questions I am here. Sorry for the crappy formatting, I am on my phone writing this.

Source: "By Tank" memoars by Kent Tout

According to Steven Zaloga in his book Armored Thunderbolt, a post war study found that American Armored Divisions suffered, on average, one man killed and one man injured per tank lost. That is of course just for World War 2.

I want to say Hunnicutt makes the same claim but I can't find the page where he mentions it, and it's possible I am misremembering what he wrote in his book about the Sherman.

The standard AP rounds of the time were simple solid shot. Later on there was hardened caps and all sorts of variations, but basically, just a solid chuck of steel. These would tend not to cause explosions in the tank unless they hit some ammunition inside. So a shot going through, unless it hit anything vital, would have no effect. While it was likely a crewman or two would get killed when the tank's armor was penetrated, a good portion, if not most of the crew could expect to escape the vehicle.

Exceptions: HEAT: as explained by u/hobbin, the molten jet of metal and plasma would be much more likely to detonate internal ammunition stores. On top of that, if the hatches of the tank were closed, the effect would be that of an instant pressure cooker. However fuse tech was such that such weapons could only be discharged from relatively low velocity guns, otherwise the impact would just destroy the fuse before it had time to detonate the shaped charge.

There was also an American AP round that was designed to penetrate the armor and explode once inside the vehicle. The acronym of which has slipped my mind. Naturally, when it worked correctly, it was devastating.

The Russians also took to using heavy self propelled guns like a sledgehammer, knocking off the turrets of German tanks with direct fire from 152mm howitzers.

Since the first part is extensively answered, to the casualty rates:

To my knowledge the casual rates were very evenly spread amongst the crew.

• The commander had the problem that he was usually killed if the cupola was hit, and especially commanders often operate over the hatch (actually a while after WW2 it became standard procedure for commanders to only button up in the utmost emergency).

• Gunner and Loader are in the turret in front of or next to the commander - consider that the turret usually is the easiest part to hit since the chassis might be hidden behind small terrain irregularities, but it also is well armoured on most vehicles.

• Driver and in many tanks a radio operator sit in front of the hull - probably the most vulnerable of positions, when it can be hit. Gunners would usually just aim for the silhouette, and 1. in many cases the glacis has weaker armour than the turret 2. at times shots would bounce off the turret into the chassis below.

• And then there are plenty of penetrations that would simply wreak such havoc inside the tank that it doesn't matter where it originally hit anyway, and only lady luck could get one or two lads out of there!

It can well be that the distribution has changed these days as the conditions have changed and there is less variety in tank shapes and types. I think these days driver and commander are the most dangerous positions - commander for those tanks that have vulnerable cupolas or when they have their hatch open, driver because he is most vulnerable to mines and IEDs.

That depended mostly on the type of tank driven. Some tanks where likely to blow up and burn very fast while others where more resilient. The type of ammo used and the gun that fired at you is another big factor.

German tankcommanders often had high casualties because they often worked with their heads stuck out of the tanks for great visibility. That also meant they where easily taken out by schrapnel and bullets or chance hits on their positions.

As a follow up question, what would a tank crew do if they were forced to bail out of their tank?