They cost memory. No money though.
Custom maps in minecraft can usually be downloaded for free.
You can't read rules for custom maps. They will be at the start or on the forum page.
No, it's not legal to sell Minecraft maps/mods.
SkyBlock is a great map.
It depends on the map.
Yes, you download it then plop it in you saves folder
Unfortunately, no, you cant. Only on a PC or a Mac
There are most likely many. One of them is the lost custom map.
Yes, it is only a custom map. All custom maps are free, and you should never have to pay to play one.
You use any kind of editor, like MC edit, and you just load
You can download them now from places. It's just a lengthy set up though.
Not completely, many people make Minecraft maps for fun and for personal use without charging. They may ask for donations for the hard work they put into their maps, but many of the maps would not require a fee to use.