Are parameters like temperature, humidity, wind, rain and snowfall important for boats and ships (large and small ones) that travel on rivers? In which way are the ships or the crew affected, and to what extent is the weather important?

Most weather has limited or no impact. However, fog or haze reduce visibility, slowing things down. Really cold weather freezes the water. That really slows things down! Wind is usually OK, but during a big storm, things slow down. Often, boats go for moorings before a big storm. Ships and crew not really affected by anything less than really cold causing ice. Up north, winter prevents much boat traffic, so major effect there. Snowfall, humidity, rain have little effect, though big rains can cause flood waters that interfere with traffic.