I recommend browsing Bushibuilder.com to look at the curve of some of the decks there.
Your curve in the dynasty and conflict deck are different, and depend on your overall strategy. If my plan is to buy a 3 cost character with 3 fate every turn, I will play enough of those so that one will flip on my provinces when I draw 4 fresh dynasty cards. I will also be including enough 1 drops so that I can usually buy these to play around way of the crab. The conflict deck in this case will have close to half of its cards at cost 0 because my fate is being spent on the dynasty side of things.
I could also go the opposite way and spend 1-3 fate on characters in the dynasty phase and use my fate on cards like a fate worse than death or conflict characters.
As for must includes, in the conflict side, the big two are banzai and court games. Not all decks play banzai and court game, but you will play at the very least one of these and often you still play both. On the dynasty side the neutral staple is favorable grounds, which makes it in many but not all decks. (you will play it if you plan to invest heavily into one character each turn)
Influence is spent based on what you need for your deck to function. Often, phoenix will splash for attachment removal because that is what it lacks inside of the clan. Other clans will splash for cards that make them more powerful. It depends on what your deck is lacking. You do not need to use up your full influence, but at least the first 6 infuence usually ends up spent.
As for provinces, it depends on the clan. Phoenix will use Shameful display to leverage its high glory. Phoenix won't use Pilgrimage because it doesn't work well with Display of Power. This is one of many examples. Some decks will choose provinces that are hard to break because they want a longer game. Others choose provinces that give themselves a speed boost when they forgo defending it. There is even combination of the two approaches where your row has 2 really tough to break provinces and 2 sacrificial ones.
Another concern for provinces is the distinction between those with a repeatable effect versus those that do something once. The former are weaker effects, but they are good against clans that don't break provinces but try to have unopposed conflicts in order to dishonor you out of the game.
As for holdings: The number depends on the overall strategy. In the example where you are buying 1-2 characters each turn, you might want about 12 holdings so that you can buy your characters and reap the benefit from your holdings both. The more holdings you play, the more you need to be able to spend your fate on conflict cards, too.