There Engineer

1. In my world Chinese wiki, you can find out the basic usage and the basic format of each command by searching for commands. If you want to advance:
NBT, please find "block format" and "player. Dat format"
scoreboard, please find "scoreboard"
JSON text, please find "command"

target selector, please find "command"

in addition, The structure block can only be used in the creation mode of cheating, which is equivalent to the upgraded version of the / clone command. To understand its usage, please look up the "structure block"

all the above items are searched inside the wiki, not the Internet
if you have any questions, you can add me.

2. Hello, the original version has no direct order to call him
his can be seen in mod
there is another method:
design a command box group, and you can define his skills, movement mode, etc

3. Even if it is the original computer version, there is no such instruction
it is estimated that the instruction of the computer version only gives you a head with his skin
the mobile version can't give user-defined head, so it can't realize this function
however, you can change the material of the head of the mobile phone version, turn it into his head, and then put it on
please adopt!