Well then Clockwork, I've taken your questions and looked at your sheet and have a good deal of suggestions to improve your character build. As for a Dual kith, it is a legit merit to take for your character so long as you pay the proper amount of Merit Points for the Merit at character creation. As for your character, I feel you don't quite get the point of making a World of Darkness character. World of darkness characters should represent actual people who could exist in the world. From looking at your sheet, you did a lot of Min-Maxing with your skills while not taking some vital skills that would better round out your character. Remember that having a 4 in a skill means you're an Ultra-Professional. Using medicine as an example, a 3 dot medicine person would be an experienced practiced doctor who would likey have their own practice, while a 4 dot in Medicine would make you a world class brain surgeon and 5 would make you one of the best medical doctors in the world. For this reason, I have a restriction at character creation that no more than 1 skill can start ranked at 4 (And no rank 5 skills to start), although you're free to raise them with XP in game.
As for suggestions to round out your edges, here is my breakdown.
For attributes, your Manipulation Score is WAY too high. First of all, NEVER buy 5 dots in an attribute at character creation as the 5th dot costs 2 allocations. Your attributes appear to be ultra-high for a standard build. The spread is 5/4/3, which is 5 dots in one area, 4 dots in another area and 3 dots in a 3rd area.
Now if you want to be Ultra-Manipulative, a 4 is more than enough, heck even a 3 and increasing your composure to 3 would be a good idea, as while manipulation is good for bending people to your will, Composure is useful for keeping that "Poker Face" in a social situation and gives you more willpower. So a 2/3/3 spread might be the more ideal. Now if you're putting social as a secondary, then a 2/3/2 would be recommended.
For physical attributes, it seems you're a stealth buff so a 2/4/2 spread might work well for a stat spread. Of course if you want to stronger or have more health levels and endurance then a 3/3/2 or a 2/3/3 would be a good spread.
For Mental attributes, a flat 2/2/2 spread is the safest bet. Although as you seem to like being perceptive, you might get away with a 2/3/1 spread so long as you can back it up with a 3+ composure score to balance out a low Resolve.
Now down to skills.
For your Mental Skills, 3+ in investigation makes you on the level of an experienced police detective. The problem is that you lack the education to justify such a high skill. You have 0 dots in academics which means you have poor formal education and an inability to do research (Which is a wits or intelligence + academics pool). My suggestion would be to lower your Investigation to 2 and put a dot in Academics so you're not completely boned when it comes to intellectual pursuits. Remember that if you have 0 dots in a mental skill, its a harsh -3 die pool penalty meaning unless you got some MAJOR bonuses you'll be rolling a chance die for any research based checks.
For Physical Skills, you're slightly more balanced here. A high athletics is fairly justifiable as that covers climbing and general physical pursuits. Your high stealth fits considering you're a darkling although you might consider lowering it to put the point somewhere else. A 3 in weaponry is somewhat iffy though considering that makes you on the level of a professional fencer but you're free to support it in character by some kind of background justification. The only real thing I would ask is that you put a dot or two in survival. Darklings often have to live in hostile environments and thus having a dot or two in survival is something many of them pick up. Not to mention Survival is needed to navigate the hedge, without any dots and you'll easily get lost and that can be a BAD thing in the hedge. Maybe raise your larceny to 2 if you're going the thief route as that covers slight of hand, lock-picking and bypassing security.
Your Social Skills are a REAL mess. I can see having a good Persuasion and Subterfuge as good, but you should also buy some Streetwise or else you'll know little about the Street-level interactions. Some empathy would be good to sense lies, intimidate to make the best use of your dark nature. Maybe a dot in socialize if you want to work a crowd.
Your merits even out ok, that's just fine on your sheet.
Now as for Contracts, I would not recommend spending all your allocations on one Contract Group. Be more diverse in your picks. Contracts of Smoke could be useful for stealth stuff. Contract of Mirror would be good to improve your disguise ability. Or if you want to affect luck, take contract of Heath 1 and 2, no 1 for the ability to inflict curses on a target causing them to lose dice or Favored Fate that can give a +4 die bonus to a roll. Hearth contracts are good as they don't require a roll to use, just a point of glamor and they work. Just remember though that they have Bans that need to be adhered to.
Now as for some final issues:
1. You need to pick 4 Specialties for your skills. Suggestions include Stealth (Moving in Darkness), Weaponry (Knives), Persuasion (Fast Talk) and Investigation (Enigmas). Of course feel free to pick a spread that works best.
2. Remember you also have 20 starting XP to round out your character. Maybe buy yourself an extra attribute, some skills or perhaps some more merits.
Anyway there is my 2.0 cents on how to improve your character. Hope that breaks things down for you Clockwork Bear