The warlock trainer in Ironforge is in the Forlorn Cavern. To get to the Forlorn Cavern, you can head east from the Mystic Ward or west from the Hall of Explorers.
ironforge
A witch but that is not a class in WoW.
Yes
Easiest way is to take the tram from Ironforge to Stormwind.
In Silvermoon City (and the Blood Elf starting areas) are Warlock Trainers. Simply ask a guard for directions by right-clicking them, and selecting "Class Trainers" and "Warlock". An arrow will appear on your map towards the trainer. Note that a warlock can train with any Warlock trainer, regardless of race. It does not need to be a blood elf per se.
Ironforge Tinkertown
In popular culture, a warlock is a male witch.
Ironforge is located in Dun Modr
You have to reach Exalted with the faction, so to get a Ram you need to be Exalted with Ironforge, for example.
The Deeprun Tram, an underground train running from Stormwind to Ironforge and back, is located in the Dwarven District
The Voidwalker is a warlock pet you gain at level 10 after you finish the quest, "The Binding".
No pets? A Warlock without a pet is like a warrior without a sword. Just plain idiotic.