There are Strategus-like browser games that are out there. Not exactly the same, but there is. However, nearly every game is somewhat similar to one another. The only difference is, how similar it is. For example, in Travian, you don't have villages, castles and cities - but you still can customize your holding in your own manner. Have one to focus on the grain, so that you can feed your troops, one another merely for recruitment, so you can have cheaper and faster troops than anyone else can every have, et cetera.
My suggestion would be to have three main type of fiefs. Villages, Castles and Towns. And let the players have a chance to customize those fiefs, if they wishes so. Villages can have two different customization, for example, one merely for food, which would support the armies, and one another for production of other goods, for more money and taxation. But also let people have more than one customization in their fiefs, if they wishes so, with some sort of penalty of cost. A cost that would be higher than having an another fief, specialized in that manner.
I like the possibility to customize what you play. It is good fun and makes you do whatever you want. However, remember. You don't want fiefs to have different names every other week, or even month.
I like the taxation of crossroads / bridges, legally or otherwise. Making the parties to move 2/3x faster perhaps, on such roads, than they would normally do in other type of terrains would actually be great, so that people may chose to "try their chances" OR go slower. Those who are moving on such roads should also make people more easily noticeable (2/3x more?) than going slowly, et cetera as well.
You should however not be forced to be at mercenary camps, to recruit troops. Especially if you are holding a fief. Recruiting troops in your own fiefs should be possible, with a penalty to your population. So you have to decide either to recruit and have a smaller growth; not recruit and be defenseless, however rich, or not recruit in your lands but recruit from the mercenary camps, with a higher cost.
Lord & Claims sounds too... meh. And Terra Nova? AFAIK, there is a game already with that name, and it doesn't really fit to the possible lore and magic of the game.
Last but not least, the current map would be okay for Alpha or some shit; but you have to have a better one, if you want even some success.
This game would be hard. Not because of any programming shit you might face, but because there are big titles out there, mmorpg's, and you need to be more unique and better than that. Though I hope you succeed.