Dou itashimashite is a standard phrase taught in most textbooks. Realistically, there's any number of ways, ranging from "kochira koso" (I should be thanking you) to "Iie, iie," (No, no [As in, 'no, it's no problem']) to "Hai, doumo."
Welcome is Irrashai or Irrashaimase... 'Youkoso.'
This phrase cannot be accurately translated, as even in English it is largely incoherent and ambiguous in nature.
Masachuusettsu e youkoso.
O-kaeri nasai Okaerinasai.
It can be translated as 'Gakkou e youkoso,' written in Japanese as: 学校へようこそ
Ariga'to mashti'. Arigatou Gozaimashita. Visit www.japanese999.com -- "Dou itashimashite" = "You're welcome" (when answering thank you)
White when translated from English to Japanese is shiro for shiro means white
Dog in Japanese is 'inu'.
Chocolate is 'chokoreeto' in Japanese.
Owari
Domo.
Koibito.