Answer: There are many places - even right in the official Minecraft Launcher! If you go to the version in the launcher there are options to download and install the older versions of the game, but they're not wholly accurate. There remain some issues with sounds, as the big thing that I personally don't like. It uses the new sounds instead of the old ones - talk about ruining the magic!The most common launcher is Betacraft: https://betacraft.uk/ This one has support for the older versions and properly downloads the sounds. They also run a server that is quite active!There is also Oldschool Minecraft (who are not affiliated with this group) but they also have their own launcher and server: https://oldschoolminecraft.com/If you are going to play one of the mods linked at the end of this post, which I highly recommend that you do, you should use PolyMC - a launcher that lets you have as many separate Minecraft installations as you want - each with their own unique instance and settings. Nothing interacts with each other.
Answer: This can be a complicated decision but I suggest you try out one of the following:Alpha 1.1.2_01 - this was the last true, bug-free alpha version before the game switched to the vibe we have in Beta. It features only 1 biome, bright green grass, infinitely spawning passive mobs, no long grass or alternate tree types, and a really charming lighting system where each block is light at a different "step" in brightness. Unlike now where the lighting is smooth.Beta 1.7.3 - This is the most complete, bug-free Beta version before the game switched to the vibe that is alive today in Modern Minecraft. It features the first implementation of biomes, infinitely spawning passive mobs, the nether, a variety of tree types, and a generally larger block palette than Alpha.
Answer: As do many - if you'd like to play more "updated" versions of Alpha or Beta - I recommend checking out one of the following mods!
Not So Seecret Saturday - A mod for Alpha 1.1.2_01 that retains the look and feel of alpha minecraft, with reworked Multiplayer, performance enhancements, and many updates to the base game!
attempting to create a more "finalized" version of beta Minecraft while
also maintaining the look and feel of the game pre-adventure update. BTA
works very different from other mods as it acts as more of a “fork” of
Minecraft, than an addition to it.