Like most questions in this category, there is no way to identify a single talent that makes or breaks a warlock. Simply play around with the talents, or ask an experienced warlock player advice on what talents to take should help you much more.
It depends what you want to do. For PvP, I find a destro/demonology build best, but if raiding an affliction/demonology build is brilliant.
Undead.
The most evil class, in my opinion, is the Warlock because you can be a Demonology Warlock and a Destruction Warlock.
You get pets :)
The warlock
Yes.
Just choose "warlock" under the character selection menu. Well first of all you should of put how can you be a warlock in world of warcraft that question is very misleading
Hunter pets need to be level 20 to get their first talent point. From then on, they gain another talent point every 4 levels. ***Note that Beast Master hunters who have the 51-point Beast Mastery talent also give 4 additional bonus talent points to their pets. Also, Warlock pets do not have talent points.
In popular culture, a warlock is a male witch.
Incinerate can be learned at level 64.
One can find a guide on World of Warcraft warlock PvP builds on noxxic dot com. Additional information can be found on wowhead dot com and wowwiki dot com.
The warlock cannot lose his/her dreadsteed no matter what, even if you delete it on purpouse you can still get it again.