GhostwriterDoF: Concerning your random world generator, land masses, oceans and rivers.
You might try having the primary functions focus on just creating the continents, defining a minimum distance that they can be from each other, and a maximum percentage of land to water ratio for the type of map, small, medium or large (and perhaps have an option for creating a map with just small islands).
Also try setting parameters for the maximum and minimum elevations / depth, whilst defining a larger percentage of "flat" area that will still give you peaks and valleys. Then the generator can use some small functions to shape mountain ranges, valleys, plains lands, and possible inland lakes and run smooth transitioning process between these regions.
In this way the random generator can run a process at the end to fill the rest of the map with water.
You will probably have to create separate river definitions (if you want river barriers / crossings to be part of the game), to have two or three generic river types, for the textures to match the types of terrain (rocky, grassy plains, snow and sandy banks, as examples). Rivers could then be added by the generator near the end of the process to connect the larger bodies of water, following the contours of the height maps.
In the final process, you could add the temperature zones, for the various regions, unless you want to make the whole world be climate oriented. Hope that is helpful. ;)
Right now I'm just playing around to find functions that work and make decent looking maps. I will probably try and do as you suggest once I'm satisfied I know what I'm doing and I'll start putting in the various parameters and setting things a bit less randomly.
Currently working on wind for realistic moisture distribution, but it's not yet playing ball...
