Do avocados spawn in minecraft?

Nopes

Thats impossible, you have to plant them

I think they do once you level up enough to get seeds

No, Avocadoes are not in Minecraft. You need a mod, which basically alters the game.

There are no avocados in minecraft.

Not without mods. If you are playing on the PC you can download mods that add avocados. The best mod I've found for this is "Pam's HarvestCraft".

The crops in vanilla Minecraft are: Wheat, Pumpkin, Potato, Carrot, Sugar Cane, Cocoa, Apple, Watermelon, and two kinds of Mushroom.

Not unless you have Mods or a Resource pack that changes something else to look like them.

WHAT? NO UNLESS YOU HAVE MODS you NOOB

No. Only in a mod.