Newbie, Need input and advice

[swotavator]

Hey all,
This is my second post. I am a true cartographer enthusiast and a really big fan of RPG's - Ultima in particular.

I am interested in starting a majorly huge undertaking to reimagine Britannia. I want to consider:
Size and scaling of the continent
Political and demographic issues
Economy and trade routes
Geology and land formation
etc.

I intend on using this project as a means of teaching myself Photoshop, Terragen, L3dt, and others, and I suspect it will take a LOT of time. I would appreciate help and input, especially from other Ultima fans.
As a finished product I intend on producing:
A highly detailed heightmap (in 24kx24k pixels)
Nice renders and flybyes
A pretty photoshop map
A hand painted historical looking map done on true parchment (goat skin)

I have a question and a few pictures I would like some critique on.
First, the question. I want to make a thread where I can track my progress, but I am not really sure where the best place to start it is. Any advice?

Also, my progress.
The files:
1. - a mockup of a heightmap that I created by piecing together DEM's of malaysia and indonesia to create a HF of britannia (original is 8192x8192)
2/3 - Map A/Map B - these are concepts I made of shorelines. There are aspects of each that I like (I highlighted them) but ultimately I am not qualified to identify which appear to be geologically correct. Map A, to me, seems to have more character, and Map B seems to me to be more geologically correct, but I am not sure. pI ultimately intend to perhaps merge these. Any advice on what to change in either? The size I am shooting for is about 500 Miles for the continent. Thanks