Translation:One kilogram of beef, please.
So wait--is "cow" ぎゅう? Does ぎゅうにく = cow meat? And milk is にゅうぎゅう--so is that related to cow, too?
Cow = 牛 / うし / Ushi
Beef = 牛肉/ ぎゅうにく/ Gyuuniku
Milk = 牛乳 / ぎゅうにゅう / Gyuunyuu
ぎゅう is the on'yomi (Chinese reading) of 牛 which means cow. The kun'yomi (Japanese reading) is うし. Normally in Japanese kanji that are alone are read by their kun reading, and kanji that are part of a multi kanji phrase are read by their on reading. So if you are talking about a cow you'd say うし, if you are talking about cow meat or milk you'd say ぎゅう(and then にく or にゅう)
No, because quantity always precedes the verb - in this case it should go between the wo and the verb (kudasai) - in another sentence it would go between the verb and the last particle before the verb.
I believe you can say "ikkiroguramu nyuuniku o kudasai." Depends on what u wanna emphasize.
There needs to be a の between 一キログラム and ぎゅうにく so that the number can be placed here and modify the noun in this way.
for what I've heard from friends studying in Japan, most people there have rarely said ichi for mostly anything that counts with one such as one minute (iffun) and in this case, one kilogram