You simply join a multiplayer creative server and hit Ior E. Or go into a single player world with cheat commands enabled and type /gamemode 1 to spawn in items and blocks.
you have to put yourself on the ops.txt in the minecraft server folder
Command blocks currently can not be crafted. In creative mode the command /give YOURPLAYERNAME 137 1 will give you 1 command block (all you need in creative).
Try: 383:99
feed a bone to a wolf you might need to give it more than one and you get bones from skeletons unless you are in creative mode
You can ask the server admin to give you permissions to build on your plot depending on the plugin of creative plots they have.
You cannot get command blocks from the creative inventory, however you can type in a command to receive one. Press "T" on your keyboard while in-game and then type /give (your username) command_block.
As with everything, it will depend on your personal opinion. Minecraft allows you to be creative and build anything you wish. If you're unsure about whether or not you'd like it, check out videos of people playing it on YouTube to give you an idea about the type of things you can do.
By either going into creative mode and getting a Spawn Egg, or by activating "Cheats" in Survival mode and using the command "/give (Minecraft Name) (Number) (ID Number for Spawn Egg/Name of Spawn Egg)"
You can't really cheat, but there are some mods (specifically, Single Player Commands and Too Many Items) that let you give yourself items. There are also inventory editors that let you edit your inventory and give yourself items.
You can't pick up monster spawners in Minecraft. You can use a mod like too many items to give yourself monster spawners. To break them, the quickest way is a pickaxe
There are no dolphins in minecraft
Yes, you can build a Nether Portal in exactly the same way as you'd do in survival mode.