Don't apologize for the long post. They're good thoughts to consider with a new map.
I'd suggest treating the border design really loosely. Right now it looks a little like the borders were imposed from space. Rivers, mountains, resources are usually the defining elements of borders. Let the map grow and then strive for a natural border line. Its unlikely to be equal and especially in a medievalesque setting its unlikely to be simple and few. Don't stop yourself from changing or developing them as the map progresses.
Alternately you can have a region of petty lords and define the region but not the internal borders...
What sort of political units are going to exist? Any regions subservient to others? How do the races interact and whose authority do they recognize? Is the coast the most densely populated? Often, ease of travel makes the coast the easiest to settle and have commerce with. Does the setting have more than horses? Are there political units big enough and thoughtful enough to build and maintain road networks? What about Rivers?
It takes a great deal of organization and structure to have a large kingdom\country. The Romans are remarkable for the size of their Republic\Empire but they had huge problems with provinces, generals, local leaders etc.... What binds a big region together? This is especially true if your continent stretches from the Arctic? to the Equator.
Countries may make claims to large regions but for games its sometimes more fun to have chaos between developed centers. Its very modern to have a border guard and a line that says 'this is America' and 'this is Mexico'. In RPG terms there usually isn't the manpower\organization. If a country was big enough to really occupy its region they'd likely be big enough to expand into someone elses territory .
Sounds like you're deep into considering your map. Good for you. I hope I've only thrown pleasant wrenches into your thoughts.
Have some Rep