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No, you download the client from the Minecraft website. The account you register there is more important than the client data.
If you want to play Minecraft on a different version than the most recent, then you will need to look online for a Minecraft server list and make sure to include the version number that you are trying to play on.
You have to download a mod to do this. Other than that it's impossible. Look on YouTube for some tutorials on how to install mods.
The download for Minecraft for the PC is around 300kb. Installed, it will be approximately 30 - 40 mb depending on how many save files you have. It is not any bigger than an audio CD.
If you download and install a modded launcher such as Technic Launcher you might be able to find a modpack that includes Minecraft Comes Alive. Other than that there isn't any way.