Ditto and Lugia do not breed. I tried it.
You can't unless you use gameshark
You don't, legendary Pokemon can't be hatched from and egg with the exception of manaphy and phione.
you can't. it's suppose to be a glitch if lugia and the unhatced egg is in your party and a shadow lugia shows up in the hall of fame after elite four.
Lugia is located in the whirl islands
No. Lugia for SoulSilver and Ho-oh for HeartGold. Yes, you just get them at different times. You get Ho-oh in Johto and Lugia in Kanto in HeartGold, and vise versa in SoulSilver.
On whirl island
yes you can. but if you have Pokemon soulsilver, the first encounter will be a lugia and vice versa for ho-oh.
If you mean Lugia following you, yes, it can.
Shadow Lugia is only available in XD.
Yes.
lugia
LV 45