minecraft Premium refers to the status of your account (e.g. Free, Premium) while Minecraft SP is an acronym for Minecraft Single Player and refers to Single Player on the current version of the game (not classic). You require a premium account to be able to play Single Player on the current version.
single player mode on minecraft
Mineraft Sp is a hacked version of Minecraft so it's offline. I suggest you buy Minecraft if you want MultiPlayer.
no
Yes.
Not as of version 1.5.2
Nope and yes.It is like a demo for the full version of minecraft.
Well i was playing minecraft SP which is free
No. You can play Minecraft singleplayer on any type of computer that's able it run it.
if you mean SSP then yes
Yes. However, offline servers do not require a real Minecraft account, but require Minecraft SP.
They are found in plains, in version 1.6 and above.
Nope, just means your ports for minecraft are open, and someone has your ip.