REAL noob question...

This is really basic, so apologies in advance for my stupidity!
When I have a unit in a transport, how long is my maximum theoretical charge range for the turn?
E.g. If I have a unit of Wyches in a Venom, can the Venom move 6, the Wyches disembark 6 and then get a 2d6 charge? Making the maximum 24 inches in one turn? I am right in thinking they can't run?
I ask because, as a new DE player who hasn't had a DE game yet, I can't see how this is different to any other unit in an assault vehicle. Yet I keep seeing all over the various forums that DE are incredibly fast. Am I missing something?....
Thank you in advance for helping a confused fool!!

The main issue is that you can assault from an open-topped transport, but not from any others, unless they have the "assault vehicle" special rule; Marine Landraiders, a few Super-Heavies etc.
Most vehicles don't have this rule.

DE are also "fast" thanks to:
-having Fleet, so re-rolling charge distance makes average charge ranges better;
-few of our units are slowed down by Heavy Weapon options (and even then the Splinter Cannon has a mobile option);
-our vehicles are very nippy if you aren't jumping out, able to fire more at full speed;
-things like Bladevanes on Reavers, allowing us to be offensive whilst moving 36"

It's not really different at all on the turn you charge. Except for fleet. But we have more open topped/assault vehicles and they're all fast skimmers. Much more distance on the delivery turn.

To increase your charge distance you can deploy a Raider for examlpe sideways right at the front edge of your deployment zone. At movement phase just pivot the Raider before movement to gain 3" in addition to normal 6" move.

A few points
Deldar vehicles are *FAST* *SKIMMERS*
A fast skimmer moves 12" and still gets to fire two weapons (the ravager has a rule that lets it fire three)
A fast skimmer flat outs 18" in the shooting phase.

That gives us a range of 30" per turn.
I think the next fastest, transport is a blood angels rhino, which can move 12" and flat out 12".
However, skimmers jump over terrain, rhinos must move around or risk immobilising.
So, we are 6" faster than the next fastest, without worrying about terrain,

None fast rhinos are 12" and 6" I think.

DEldar vehicles are *OPEN TOPPED*
This means they are both assault vehicles (rare, off the top of my head, thats land raiders, storm ravens, and scout speeders), and they dont have access points, which lets us get VERY creative with where we jump out from.


DEldar themselves are *FLEET*
This lets you reroll the dice when you charge

What does this all mean.
Well
12" move
18" flat out
6" move
6" disembark
10" charge (25% of pulling that off)

One (3700pts per side team) game
In two turns, I charged a unit 50" (8" charge) away and took an objective.
The space marine I was playing just looked at the board with an awesome WTF face on, (to be fair, so did his team mate, my team mate, the two people next to us, and me).

The only other thing that could do that is a 200pt Storm Raven, if it was looking the right way.
I did it in a 65pt Venom.

Fantastic, really useful and clear advice: thank you all!!