"Born of a supernatural bloodline, a Warlock seeks to master the perilous magic that suffuses his soul. Unlike Sorcerers and Wizards, who approach arcane magic through the medium of spells, a Warlock invokes powerful magic through nothing more than an effort of will. The font of dark magic burning in their souls makes them resistant to many forms of attack and arms them with dangerous power. Warlocks learn to harness their power to perform a small number of specific attacks and tricks called invocations. Warlocks make up for their lack of versatility by being tougher and more resilient than sorcerers or wizards. By harnessing his innate magical gift through fearsome determination and willpower, a Warlock can perform feats of supernatural stealth, beguile the weak-minded, or scour his foes with blasts of Eldritch power."

Source > http://nwn2.wikia.com/wiki/Warlock

In D&D 5e Warlocks are casters that don`t have magical power due his natural talents like sorcerer or study and dedication like Wizards. They get power due a pact(source > https://roll20.net/compendium/dnd5e/Warloc )

And in D&D 3.5

"Some people want power, and are crazy enough to offer their soul to various not nice people to get it. Others are simply (un)lucky enough to be descendants of those same people. However they managed to get their abilities, Warlocks wield the powers of the lower planes, which include powerful magic spells and the ability to shoot hellfire out of their hands." Source > [url=https://www.dandwiki.com/wiki/Warlock,_Variant_(3.5e_Class]https://www.dandwiki.com/wiki/Warlock,_Variant_(3.5e_Class)[/url])

So in NWN2 a Warlock is a a "Dark Sorcerer"?

Classes can differ quite substantially between editions. I wouldn't stress too much over the differences between 3.5 and 5th edition Warlock.

With that said, the 3.5 warlock you link to is not the official warlock. Generally anything from dandwiki.com is going to be unofficial fan-created content. The official Warlock was never released under the OGL, meaning you're not allowed to post descriptions of the class online (unlike classes like the Wizard which were released under the Open Gaming License and can be used and republished under the conditions of that license, which is how sites like d20srd function. Anything that's missing from those sites - for instance, you'll notice 4th edition isn't listed there - isn't released under the OGL). The Warlock is probably one of the best known non-OGL classes for 3rd edition, possibly due to its appearance in Neverwinter Nights 2.

I can't post description here but according to another forum that i've searched, the answer is in book Complete Arcane v3.5 book at pag nº7. In nutshell, the warlock power can be passed to your descendants like sorcerer, for more details see the book.

Note that the book contains Wu Jen and Warmage, classes that aren't in NWN2 and some spells in NWN2 works different than the book.

Yes, the official Warlock is from the book Complete Arcane. I don't own the book, so I don't know much more than that and how much it differs from its NWN incarnation. A lot of spells work differently in NWN2 than in pen and paper. There are literally hundreds of classes in pen and paper D&D (as well as thousands of feats and tens of thousands of spells), and relatively few of them made it into Neverwinter Nights.

Thanks. Is possible to be a Aasimar(Planetouched) - Descended from celestials and a Warlock?

I've only played nwn2 long time ago but will have on gog soon.

There's no such restriction. Personally I don't think the level adjustment is worth it, but there's no technical rules prohibition on the matter.

I an a lv 6 Aasimar sorcerer and have 20 CHA, 58 HP and ... no attribute under 10 pts. IMHO at low level, the penalty is deadly but at higher level, the difference isn't that significant. For example, need 1k xp to go to lv 2(non ECL) or need 3k to go to lv 2(ECL + 1) is a great difference BUT at high level, you need in total 190k xp to be lv 20 without ECL, with the ECL +1 penalty, you need 210k. The difference isn't that big at high level.

One question. If i pick the Red Dragon Disciple, my ECL will go from ECL + 1 to ECL + 2?

I would agree with that assessment, but you are playing through the low levels right now. Dragon Disciple is a class, not a race, and has no effect on ECL.