1. Monster spawners can be found underground, this will be zombies, skeletons, spiders.
2. Blast mining does not work in the mining world, only in the nether.
3. I am unsure, however I do not think so.
4. it is suggested having homes in the main world instead of the mining, due to the fact the mining resets every 1-2 months, aswell as you cannot have locks in the mining world. The mining world is like said, to mine.

 

Hey! Welcome to ECC!

To answer your questions:
1) Monsters will spawn in the mining and nether worlds, they're just quite a bit rarer than standard singleplayer. To get bones I'd suggest locating a skeleton spawner, and as for gunpowder, well, even older players have troubles getting it. Just get money and buying it is your best bet.
2) No, you can only place/use TNT in the nether world.
3) They don't damage the terrain.
4) Mobs do still spawn in the mining world, just rarely. I can in no way suggest building in this world, however, as it is reset every month. Get yourself a nice plot in a protected town, there won't be any mob spawns but it won't be reset.

 

You can build anywhere in the mainworld outside of a protected town, however, it will not be protected and can be easily and legally griefed by other players so I would not suggest it.

 

There are no hostile mobs in the main worlds (Legacy & Rising).

 

No, I believe only in the nether you can blow things up but, if it is in the "Wild" or unprotected (town) area, it can be greifed without being penalized. I would suggest you buy a plot in a town. The average cost is about $1,000, so relativelycheap.

 

Creepers haven't spawned AT ALL during my 3 years of playing ECC. As far as I'm aware.

 

We do??

 

No, mods, not admins.

 

OH... All mods or just the blue ones?

 

blue mods

 

Unlike others, I actually do recommend building a base in the unclaimed parts of Rising or Legacy (the main worlds). As long as you hide it, lock your chests and set your home there, it will be quite effective.