While I'm open to the idea that it takes more than money to convince an NPC (provided you don't say they will deny payment by state X), I'm going to say no to individual NPC traits. Traits are bonuses meant for the players to customise their nation according to their intended play style, and give them an edge over the minor countries.
Prototype Spreadsheet
You can see the Espionage sheet solely to get an idea how it works; all players start with the same amount of money invested in their own espionage. This serves as your DEFENSE; if a player with 1000 Espionage assaults you, they have a 50% chance of victory. Do not neglect your defense, my friends.
The minors are missing from the espionage sheet, but that's so you don't get to see exactly how much you'd need to pour in to overthrow them. Overthrows aren't an every day occurrence; they will take considerable investment to work. Investments in a foreign country's espionage can either be used to protect the current regime from outside attacks, or assault said regime to impose a favorable one.
The Influence tables took some work to properly tweak, but for the most part they are balanced so each player gets the same amount of money from clients on Turn 1 (I gave 3 players some credit of one gold to even it out). Regardless of what Ailedhoo's up to with the NPC in question, your influence represents your business interests in the country as much as your diplomatic clout, and as such you earn a percentage of that state's "client value" based on how much of the total pie you own. If they have a value of 10, there are 1000 points, and you own all 1000 points, you will take 10 gold from them each turn.
Keep in mind influence can be purged by coups. Theoretically angering an NPC enough will justify Ailedhoo purging said country's influence (i.e. repossession) but logically if it gets to absurd amounts I will rein such things in.
Influence amounts are controlled by me, and these are ways to increase/decrease it:
Increase
-Intervening in the government's favor in a conflict logically will boost influence.
-Giving the state money (the usual method) boosts influence.
-Diplomatic moves, even indirect ones, that would be of benefit to that country will help score points. Standing up to warmongers, for example, will logically make most countries like you more.
-A coup in the country will increase your influence, logically. You can specify for a coup to purge influence of other nations; take heed that these events make it onto the news and could earn the ire of other countries.
-Provided there's no one willing to assist them, a show of force can actually increase influence with a country. This is a global world though, so avoid being too open about it.
Decrease
-Belligerent statements logically hurt influence. Stating a particular racial group is inferior, for example, would most certainly curb your pull with any states of that group.
-A coup or protectorate by another nation can potentially reduce or outright eliminate your influence
-If they are not your client, being aggressive towards them will shrink influence
-Aggression towards neighbors also will hit influence, unless that nation is unable to find someone who would be able to provide for their defense
-Logically if you anger a country enough they can purge your influence unilaterally (think Iran or Cuba with American assets).
The one time aggressive behavior will increase influence is when you conquer the country and impose a puppet state, or threaten to invade them if they do not become a protectorate of yours. Logically either of these moves will hurt influence with third parties, however, so use them sparingly. The world's global now, so shows of force alone won't bully neighbors into submission; they'll just go looking for outside help instead. If they can't find outside help (Cuba having the USSR to defend against the US, Taiwan having the US to defend against China, etc.), they will increase influence instead out of fear.