The play by post section of this board has plenty of examples of the game in action. One of the best is the Cradle of Darkness game found at these links.
http://www.jimbutcheronline.com/bb/index.php/topic,28668.0.html In character
http://www.jimbutcheronline.com/bb/index.php/topic,28667.0.html Out of character

Play-by-Post:http://www.jimbutcheronline.com/bb/index.php/board,32.0.html

Don't worry about it, everybody has to start somewhere.

So if you're looking for somebody who's both strong and smart, it'd be good to start with an appropriate High Concept. To tie that in with the search for vengeance, the High Concept could include a reference to revenge, or if you feel like it the revenge thing could be the villains' trouble.

Now, since this is a main villain and a fallen angel to boot, there's no need to stay away from really over the top aspects. For example,  an ok High Concept could be AN UNSTOPPABLE EVIL. But that's a little generic. What would be really good is if the things you already know about the character could be tied into the characters' history. Like, if this Denarian is famous for causing massive amounts of violence, a good high concept might be THE SLAYER OF CITIES, to show that the Denarian is someone to feared and never underestimated, as well a terrible, evil, no good bad guy.

So the real question is, what's up with this guy? Where did they come from? Why do they do what they do? What have they done so far that's really impressive and dramatic?

If you can think of answers to those questions, you'll have the outline you need to turn your character concept into aspects.

You can do any amount of time skipping you want or need to get to the good parts of the story.

A piece of advice, however, is not to make huge or inconsistent time jumps without a reason. It can trivialize the player characters lives and problems, or the players' attempts to prepare for serious trouble when given time.

Since you've set the "big event" where all the action is after quite a bit of time, then maybe the story should be about the players getting ready to deal with it. Making allies in their hometown, seeking out information or equipment to help them with the inevitable battle. Setting up a counter ritual would be a pretty cool solution, as long as it was appropriately epic.

Side jobs are fine, but anything unrelated to the main story probably isn't worth spending more than a session over.  But example trouble from 'stock' bad guys could include
-Being blackmailed by an RCV into helping out with Red Court political plays
-One or more Denarians moving into the city and tearing it up looking for a coin that's been locked up by somebody with good intentions
-Ghouls acting like they usually do and eating lots of people. Maybe they're having a party?
-A Faerie steals one of the PCs names and starts pretending to be them, causing trouble for everybody
-Dr. Doom. ALL SHALL KNEEL BEFORE DOOM! Why? Because it's funny, that's why.
-A demons been kidnapping people around a hidden entrance to Undertown.
-An ordinary human arsonist seems to targeting the magical community.

And a ninja!

Shovel (for hiding bodies)

Actually, now that I'm thinking about it, a shovel might not be the best way to hide a body in all cases. While it may specifically be useful for areas with loose earth and lower populations, cities, arid landscapes, swamps and so on all have different requirements for getting away with violence. A more likely tool set would be a number of large garbage bags and a saw.

Then, as long your hunter has an excuse, it becomes much easier to transport bodies to wherever it is they need to be hidden. The stomachs of some native wildlife or livestock would be a good choice for most corpses, but lakes, interior walls, volcanoes or of course, graveyards would all be natural locations to leave the dead without much chance of them being found.

A 13th century crusader eh?

If he's an actual knight (not like a Knight of the Cross, just a normal knight), then he's got several things going for him, equipment wise.

1. Plate mail.
2. A horse.
3. Possible access to early gunpowder, if he's rich or knows rich people
4. An order of knights that act as contacts or potential backup
5. Possible access to rare items, like a book of prayers, holy artifacts, a sword made from the finest steel in known world, a famous shield passed down a family line, etc.

If not an actual knight, you may want to consider making him related to a wealthy merchant. High-quality or rare equipment can become difficult to justify having for people without noble blood or money.

As for items specific for protection from vampire attacks, go with holy stuff. For a vampire hunter specifically, it's pretty easy to justify them seeking out divine aid against bloodsuckers. In addition to giving your character more things to satisfy a catch with, these sorts of objects can be used as the basis for declarations and maneuvers during combats.

However, against mind control/charm attempts, you're probably going to want to focus on skills or stunts over equipment. Equipment can help, but 'a pure heart' or 'a will of steel' will probably go a lot farther than anything most characters would reasonably be carrying around.