yes as soon as you've downloaded the mods you can play the mods while offline.
Not in the current Vanilla (Minecraft without Mods) Minecraft, no. But their are a few Mods out there that will make that possible.
Not without mods.
Without mods, you can't.
you can get mods off websites like minecaft mods that no one uploads viruses to because they would get caught and banned in seconds, i reccomed minecraft mods.
There is no brass in MineCraft without mods.
TNT without mods. With mods, the hydrogen bomb.
No, only when you download them the first time.
you cant without mods
Yup.
you can get minecraft mods and textures off the minecraft mods website.
You don't need a CD for mods. You don't need a CD for Minecraft at all.
You cannot make a hang glider in Minecraft without mods.