Custom maps in minecraft can usually be downloaded for free.
No
You can't read rules for custom maps. They will be at the start or on the forum page.
SkyBlock is a great map.
It depends on the map.
Yes, you download it then plop it in you saves folder
They cost memory. No money though.
There are no commands in minecraft PE as far as I know.
You cant when you delete them there lost forever. Unless your worlds backed up.
Unfortunately, no, you cant. Only on a PC or a Mac
there are no mods in minecraft pe i hope there will be
Yes. It is possible to crouch in the minecraft pe.