Thanks so much for reading @gentleshaid. To answer your questions ;

• A swamp is just a type of wetland; there are four types: Bog, Fen, Swamp and Marsh. Maybe I'll do another post on them

• On the type of water found in wetlands, it depends on the source of water to the wetland.
  If the wetland is found around a freshwater body, it's most likely a freshwater wetland and if it's around a brackish water body, it'll be a blackish wetland.

The source of water also determines the type of wetland it'll be (bog, fen, marsh or swamp)

• I referred to moss and grass as being dominant in wetlands, there are definitely a whole lot of other plant species that can be found here