You'll have to trade from Pokemon FireRed or LeafGreen.
u cant
You cannot catch Diglett in Pokémon Emerald, you can only get it through trading.no where you need to catch it in L.G OR F.Ryou can't but you can get him from leaf green or fire red
You can't catch one anywhere in Emerald. You'll have to trade one from FireRed/LeafGreen.
You can't catch Diglet on Emerald. You can obtain it from trade or hack (something I have almost no experience in)
Buy the TM Dig or catch any Pokemon that already knows it. A common one is Diglett.
no you cant catch diglett on Pokemon ruby because diglett is too old he comes only back in Pokemon diamond
around survival area
Nowhere, because it isn't available in Emerald. You'll have to trade one from FireRed/LeafGreen, where you'll find it in Diglett's Cave.
Diglett or Dugtrio
diglett, rayquaza, and most ground type Pokemon
No you cannot catch Celebi in Pokemon Emerald.
No I don't believe you can catch a ledyba in emerald