To download the other ones you need to make a folder in the versions folder for minecraft and put the client and JSON file for the versions in there. They all need to be named the same aside from file extensions. Once you do that, you will be able to choose that version when making a new profile with the minecraft launcher.
Minecraft regularly stream on Twitch and Mixer, and although as far as I know there has not been any official confirmation around where the stream will be available, it's almost certain that it will be available on the twitch.tv/minecraft and mixer.com/minecraft channels, as previous Minecon streams have taken place on Twitch. They may also stream on YouTube.
I know that it is live and can be watched from anywhere, but there seems to be no information on stuff like what website it will be on.
Remember those versions that minecraft pranked us with? Specifically:
Those are still downloadable! Watch this video for 2.0:
https://www.youtube.com/watch?v=PQdu9LKAdIU
To download the other ones you need to make a folder in the versions folder for minecraft and put the client and JSON file for the versions in there. They all need to be named the same aside from file extensions. Once you do that, you will be able to choose that version when making a new profile with the minecraft launcher.
15w14a is on this link:
http://minecraft.gamepedia.com/15w14a
1.RV-Pre1 is here:
http://minecraft.gamepedia.com/1.RV-Pre1
Minecraft 3D is here:
https://minecraft.gamepedia.com/Java_Edition_3D_Shareware_v1.34
Minecraft regularly stream on Twitch and Mixer, and although as far as I know there has not been any official confirmation around where the stream will be available, it's almost certain that it will be available on the twitch.tv/minecraft and mixer.com/minecraft channels, as previous Minecon streams have taken place on Twitch. They may also stream on YouTube.
https://feedback.minecraft.net/knowledgebase/articles/888012-official-minecraft-livestreams-faq