How does the faction change works?

i can't see to find any guidance on how the process works :(

anyone care to explain?

You need to create an ally level 1 with same class to be able to move your Horde characters to Ally.
Why? so the system will give you the same appearance of the lvl 1 character you made

At the moment it is free and it works only "from Horde to Ally", not viceversa ( it is NOT reversible)

When changing factions for warlock orc> human / gnom
Will I have to do quests again for pet and mounts?
change my reputation on ali?

"When changing factions for warlock orc> human / gnom
Will I have to do quests again for pet and mounts?
change my reputation on ali?"

THIS IS ACTUALLY A GOOD QUESTION!