A series of questions to ask:
1) Who is nominally in power?
2) Who is actually in power?
3) Of the various factions not in power, which if any want to be in power?
3) What is the personality of the current King?
4) What rituals and traditions are considered essential to establishing the dignity, legitimacy, and sanctity of the monarchy?
5) How stable is the current political system?
6) What are relations like with neighbors?
7) What is the overall present overall alignment of the nation?
8) What is the present alignment of the ruling class? If this is different than in
#7 , what sort of tension does this create?
9) How strong is the dissident faction within the nation, that is, the group of people with the opposite outlook on life?
10) How does this alignment tension within the society manifest itself culturally? What markers are used by the different groups to recognize each other?
11) How interwoven into normal life are the religious affairs of the nation? Are there certain roles or aspects of public life - notaries, lawyers, undertakers, butchers, physicians, certain bureacratic classes, navigators, scribes, etc. - that are wholly dominated by one or more priesthoods?
12) How interwoven into normal life is magic and the arcane? Are professional wizards common? Are ordinary people aware of the more common sorts of spells (charm person, knock, invisibility) and their capabilities and take precautions against them? Are wizards feared, revered, or are they treated as mundane tradesmen? Is it common for people to have fairies or spirits living with them in their homes, gardens, or private shrines? Do ordinary people have some knowledge of placating and communicating with fairies and spirits?
13) What ethical tension is present because of enduring local traditions that may still exist in contrast to the overall alignment. What is the societies views on hot button issues like slavery, heresy, torture, necromancy, abortion, capital punishment, cannibalism, toleration, civil liberty or how to establishing justice (that is, do they still practice dueling, formal trial by combat, trial by ordeal, etc.)?
14) What is the approximate technology level of the society?
I note that you've answered some of these fairly well. In particular, I think that
#13 is answered in a particularly interesting way because of the culture tradition of infanticide of those found physically imperfect. I would suggest emphasing the healthiness and relative prosperity of the culture, but alo create a number of unique undead to personify the consequences of this choice. The spirits of vengeful cripples, mutes, the spirits of the neglected blind and deaf, and the spirits of abandoned babies are all suitable to a fantasy setting you've created. You also need to outline the extact directions this tension is pulling society. For example, there might be a faction that thinks the solution is to make the tradition of euthenasia more orderly so as to avoid some of these undesirable side effects, while another things the tradition is itself repulsive and are trying to spread feelings of compassion toward the handicapped.
I notice that you have the eldest daughter inheriting. Is this meant to be a matriarchy (a queendom, rather than a kingdom?), or is that just coincidence? Is sharing royal power with your spouse typical or unusual in the society? (For example, the current Queen of England is not co-regal with her husband.)
On some of the questions I think you should be asking, I don't think you've spent enough time. I'd like to know more about the internal structure of the society. Nominally, the King and Queen appear to be corulers. Are things as they appear, or does one hold the real power? Are the Barons sufficiently powerful collectively or individually to thwart the rule of the monarchs? Who actually holds the purse strings? Who actually is in charge of the army? You've got a highly enfuedated setting, one of the problems with this is typically the army is actually run by the Barons (who have control over the knights), and the monarchs practically have to beg or bribe the Barons to use it. Where is the loyalty of the commoners push come to shove - to their city/baron or to their nation/queen? Note that the more effectively the monarchy gathers taxes, the more the tendency of the commoners to see the Barons as protectors, and the less effectively the more the commoners will tend to see the Barons as rapacious and the monarcy as their protectors. So, there is a tension here.
Equally, how large is the actual royal domain of the monarchy? How much real power do they have all the way out to the frontier?
You describe the military and the clergy as the more typical way to change your social station. This describes a nation with practically no middle class. All wealth and power is concentrated in the hands of an aristocracy, and the only way to get a share is push yourself into the aristocracy by rising up sufficiently to gain titles of your own. This is I would note however a rather rare situation for a seafaring nation (China might qualify) because it implies only nobles own ocean going vessels and engage in trade (directly or indirectly). If there is no nascent middle class, where does the self-motivated and ambitious commoner turn if they can't enter high society but still want to prosper? If sea faring is locked away as the province of the nobility, what about trading up and down the nations rivers? Is crime a viable alternative to wealth? Piracy? Smuggling? Banditry?
You've got a comparitively huge elven population in the nation. How do the races get along? Is it a cosmopolitan setting, or do elves mostly keep to themselves in separate almost fully autonomous Baronies? Exactly how do you manage to have a culture where physical imperfection can be a death sentence, but the elves apparantly tolerate half-elven children (or vica versa, men tolerate half-human children)?
