The twilight forest is a mod. It was never in the game that Mojang made
it is only on computer
the twilight portal is a portal that sends you to the twilight biome.
it is a mod
No, the Xbox edition of minecraft is not the same as the computer version, also the Computer and Xbox versions have different development teams. While the xbox version would be around Beta 1.7 in computer mc terms the computer version is in official release 1.4. The end portal for computer did not come out until the 1.9 beta times.
If correctly placed, only 10 obsidian blocks
4J Studios hasn't put in The End yet but there's still portal frames (creative mode only)
You will need 14obsidian if you are going to place obsidian on the corners of the portal, but if you fill in the corner of the portal with other blocks, then you will only need 10.
no only gameboy advance
I'm afraid you can only make water portals with the Aether mod. To make an Aether portal with the mod, you make the same structure as a Nether portal, but out of glowstone, and empty a bucket of water into on of the bottom spaces in the portal frame.
Minecraft is all about the account you made, you can log into that account on any computer, you are not forced to play it only on the computer that you purchased it on.
The only portal you can make right now is a Nether portal. Same with the PC version. (without mods)
only if you have this mod that gives you blocks like the mob spawner or what you want a nether portal
Right now no. Right now the Xbox version is one of the beta versions when minecraft was only on computer
No there is only pistons on the computer version
No. You can play Minecraft singleplayer on any type of computer that's able it run it.