Hi guys,
I'm going to play Ravenloft in a month or so. I've never played it before and I've only once played D&D 3.5 about 2 years ago (might be even longer). This means that I have no clue how to build an efficient character. I do have a concept though:
I love Van Helsing (the witch hunter) and Vayne, a champion from the game League of Legends. Both are rogue type characters and use (large) crossbows. Vayne also is able to roll out of the way of attacks and can turn invisible briefly to launch a surprise attack on an enemy.
I love all these concepts and I wonder if it is possible to build a character in the spirit of these examples.
My DM has little experience with the D&D system and I dont have much either. We do have some very experienced D&D players, who will no doubt max their characters as best they can. They told me that crossbows (and ranged in general) is bad.
The DM said that we probably won't be leveling much, so I imagine we will be playing characters between lvl 5 and 10. we will be playing with about 10 players.
I'd like my character to mainly do a lot of damage in combat, try to be a bit stealthy, not have too much health/armor (I hope that our warriors will be able to tank most enemies) and maybe sneak attack with my crossbow.
What kind of class progression should I be looking at for the first 6 levels or so? I'm assuming picking human (they get an extra feat, right?) is smart?
What are good (normal) weapon choices for this concept?
What feats should I be taking (pref. from the core book or players guide)?
I tried the search, but I fail at the internet I guess. Thanks in advance for any advice!
Oh ok, thanks for the advice 
If I use a bow instead of a crossbow, will i be viable?
Bow users are a lot more diverse than crossbows (almost entirely due to their ability to fire multiple times without spending an action to reload). However, they're still tricky, since (barring obscure high-level options like the Energy Bow) you can't use Power Attack, and thus they've got lower damage output per shot.
The basic relatively-high-bang-for-little-optimization-buck bow builds involve your stereotypical Swift Hunter approach, since that's a cheap way to get damage up there (including ignoring precision damage limitations on favored enemies) and it reduces most of the problems with archery down to problems of movement, which is a much simpler thing to keep track of. Although it does delay the progression somewhat, a swordsage dip here can be quite effective (Child of Shadow, Shadow Jaunt, Cloak of Deception, Counter Charge, [either Wolf Fang Strike, Claw at the Moon, or Rabid Wolf Strike depending on level; you won't use any of these], and Sudden Leap, plus one more maneuver of your choice; a second swordsage level gives a second stance (probably Assassin's Stance but any of the Shadow Hand ones are good here), an extra maneuver, and Wis to AC.).
Another alternative is looking at other per-attack boosters, such as Inspire Courage, and remembering that a quiver of Spell Storing arrows allows an archer to unload countless situationally-perfect spells at a decent rate without costing your team's spellcaster any actions during combat.
A few of the builds I've showcased in my sig are also bow specialists - the Heavy Weapons Elf and Flip the Bird - but you'd only really want to read those for ideas.
Spell Storing Arrows+Scrolls and UMD or friendly "tech team" makes you like Green Arrow or Hawkeye with specialty arrows.