They program them using code and Java.
To enhance the game, and add new things into it.
Not in the current Vanilla (Minecraft without Mods) Minecraft, no. But their are a few Mods out there that will make that possible.
you can get minecraft mods and textures off the minecraft mods website.
You cannot make a hang glider in Minecraft without mods.
While the user licence of minecraft does allow people to charge for modifications (mods), most mods are published for free.
There is no brass in MineCraft without mods.
Yes. Most mods in Minecraft are free, however you can donate to the developer to help them improve and make new mods.
As for now, chocolate is not in Minecraft. But you can install mods to add chocolate.
bearshare is not required to get minecraft mods.
there are no mods in minecraft pe i hope there will be
Yes, most Minecraft Mods are updatable.
Without using mods, you can't.