how exactly do you guys make the maps just the way you want with only certain items and even adding in lava and water. Also, is it possible for me to do this? Lastly, how do you share maps you've made on your device without having to do it over the local wifi?
Im not sure how they do but i think i got a general idea of how they do it. All they do is change the blocks that are not available in the pocket edition to pocket edition compatible blacks like the 36 blocks available. For example like changin glow stone blocks to stone or glass blocks compatible with the pocket edition. Yes you can do aswell viously if they can you can but you may need programms or something to doit and practice and for your last question iidk maybe try this link coincedently i came upon it just today like 5 minutes ago http://www.minecraftforum.net/topic/936769-host-your-own-minecraft-pe-online-server/
Easiest way to make custom maps is to edit straight from pocket edition using apps like pocketInvEditor for Android..
You can add water and lava just by placing it straight from pocket edition...
My first few maps was done straight from my phone.. For more advance editing use mcedit.