How is a soldier treated in Napoleon's army and how is that different from how a soldier is treat in say a Russian or Hapsburg army? Since Napoleon had beaten 5 coalitions up till this point, I am really curious as to what the culture of the different armies was like back then.
This varies quite a bit.
Previous to this, the French army had enjoyed superior staff work, with a full staff for planning attached to each corps. The French corps system also usually allowed for a better supply situation, which meant that a French soldier ate better than most other armies on a long campaign.
The French medical service was also better, using field hospitals and ambulances and understanding the need to isolate sick soldiers from the rest - Napoleon lost at least 30 000 wounded and sick after Prussia and Austria switched sides after his disastrous campaign in Russia 1812 - French soldiers quartered in many small towns and villages to rest after being sick or wounded were captured.
The French army was a consript army, which meant that soldiers were forced to fight. However, conscription also meant that the recruiters could have their pick at the best men and could force the men through a rigorous training scheme which created units with strong unit cohesion and well-trained and well-drilled troops capable of large-scale manouvre, as they had chances to train such actions before being on the battlefield.
The Habsurg army pre-1809 was a mercenary one, where a colonel would raise and train a regiment of volunteers and then add it to the Austrian army. At times, these regiments could consist of the dredges of society, and supply, medical and staff work could be severely lacking.
However, by the Battle of Aspern-Essling 1809, the Austrians had copied much of the French innovations - they were using large conscript formations, had started doing staff work, organising their army into corps and improved the uniformity of training and added large-formation drill.
The Russians retained their tradition of having a core professional army and raising large amounts of conscripted serfs for it in war-time. Supply and medical services were lacking even worse than their Austrian counterpart, but also improved over time. By 1814, the Russians were capable of operating in western Europe, even capturing Paris in co-operation with the other allies of the Coalition. The Russians also copied the French corps system. At Preußisches Eulay 1807, the Russians had copied the French Grand Battery tactics, devastating the arriving French corps with a thunderous barrage.
During the French invasion of Russia, the Russians also started to use irregular cavalry, foremost Cossacks, but also other groups, to raid and disrupt the French Grande Armée.