Examples are silver chloride and Pb(II) chloride.
Sea salts contain: sodium chloride, magnesium chloride, calcium chloride etc.
Because water and some salts are polar compounds. Soluble are: sodium chloride, potassium chloride, magnesium sulfate, uranyl nitrate, calcium chloride, lithium chloride, sodium nitrate, sodium carbonate, ammonium chloride etc.
The most important is sodium chloride; other salts are magnesium and calcium chloride. Many other salts are in extremely low concentration.
Sodium chloride doesn't react with water; sodium chloride is dissolved and dissociated in water.
Some salts are insoluble in water. All types of sodium chloride are soluble in water.
"Fresh" water contains all types of salts including sodium chloride, and calcium chloride. Only distilled water contains no salts, it is pure H2O
The concentrations of salts in waters are very variable and also the salt types; each water has a specific composition. For example sea/ocean water have approx. 35 g/L sodium chloride and treated tap water practically doesn't contain salts.
Many are, but not all. As an example of exception: silver chloride, AgCl.
Water solution of sodium chloride is an electrolyte.
All salts soluble in water can exist also in organisms.
The most important is sodium chloride; but many other salts are ingested from foods and water.
The most important is sodium chloride; other salts are magnesium, potassium, calcium chlorides and of course many minor salts.