Most likely because you only have a trial version. You can buy and download the full version from minecraft's website (the link is under 'Sources and related links' below this answer).
All you need to do is make an account on minecraft then buy the full version. If you do download it and you don't get the latest version you just use your minecraft password to update. If you don't know the password then you need to make a new account. If you've already bought minecraft and you forgot your password then you can redeem you minecraft gift code to buy minecraft for free. But you can only do this when you've bought minecraft before.
Minecraft accounts are already free, you can freely register one. You only need to pay if you want the full version.
If you are referring to the PC Gamer demo version, yes. If you are referring to the Classic version, no. It is very limited, and meant to be just for building.
You can play the demo version or Minecraft Classic on the Minecraft website.
I don't think they plan to create a disc game of Minecraft as they've already created a downloadable version on the Xbox marketplace.
there are no rumors for minecraft pe version 4.1
it's already out. Minecraft is in version 1.1.0 now, full release
Currently, Minecraft's newest version for PC is 1.4.7
minecraft's latest version as of June 2016 is 1.10 (The Frostburn Update).
No, it is not. Minecraft Beta is the newest version of minecraft. In order to get it, you must pay for it. You can play a free version called minecraft classic though.
There is only one version of Minecraft currently sold by Mojang. It costs $24.99 and give you access to the current version of Minecraft and future updates. You can find Minecraft Alpha codes on eBay for $10. These (should) give you the current version of Minecraft.