1. Polish and Lithuanian prisoners of war hardly had any significant differences in armament and equipment from the Cossacks. They were sent to the Urals as workers and settlers, but not soldiers, which means weapons and armor they have not kept.. When they were recruited into the Siberian expedition, they received weapons and equipment from the arsenals of the Stroganovs merchants. Probably there were, among others, European armor and weapons, since we are aware of its use. And it is possible that the former prisoners prefer the familiar weapons - but this is only speculation. They didn’t create any separate units, and probably, simply entered the Cossack class, receiving the status of "Cossack".
2. By the time the fighting began, the detachment of Ermak was about 1,500 people. It is also known that the river fleet of Ermak was about 300 large boats (they were called the Strug). The boat could hold 20 people or up to one and a half tons of cargo. Firearms had about half the squad Ermak. In addition, the boat may be set two to four falconets. How many were there in reality - is not known.
The manner of fighting in the Cossacks such. The best shooters fire out of the muskets, the rest charge and give the shooters loaded guns. This is a fairly intense and long-lasting fire. After bringing the enemy into frustration, the Cossacks attack with cold weapons. Such shooting can be carried out directly from the boats.
3. The Cossacks preferred a wick gun, as allowing a more intense fire at that time. I think most of the castles were Russian-made, although there is evidence that the Spanish arquebus were used in the Ermak detachment.
