Basically, calling a young lady 小姐 in Cantonese is always correct, calling a woman 靚女, depend on the fact that you know the person or not; and what tone you are using, is like calling her "babe" or "lovely lady" in English,
A: 喂小姐，唔該！
Hey Miss, excuse me!
Starting a greeting with 喂 is quite rude,
Better just : A: 小姐，唔該！
if you wanted to say 喂 because you are trying to get her attention, when she's standing far away from you, you can say, Hi！嗰便嗰位小姐，唔該！( Hi, the lady over there, please! )
B: 先生，你好你好！你想愛乜？
Hello, Mister! What would you like?
You really like to use 愛 instead of 要，don't you?
*要 is far more common than 愛 when you want to say "want"
Anyway, a typical dialog is more like : 係！ 請問呢位先生想點啲乜野呢？ (yes sir, what would you like to order?)
A: 我想愛一碗雲呑麵，加底，唔該。兩杯/盃(Which one is proper?)熱奶茶，唔該。同埋...而家都OK喇。留下張單(What's the proper way to say menu?)喺度先，遲啲/後嚟(Which one is used more for later?)睇下有冇第啲嘢想食/order(食 vs order)，好唔好？
I want one bowl of wonton noodles, increased portions, please. Two cups of hot milk tea, please. And...Right now everything seems okay. How about leaving the menu here first, and later on I'll see if there anything else I want to eat/order, okay?
加底 mean extra base( noodle in this case), if you want bigger portions that include more topping (wontons in this case), you can pick "large" size if the menu listed different size.
A: 我想愛一碗雲呑麵，加底，兩杯/盃(Which one is proper?)熱奶茶，唔該。同埋...而家都OK喇。份餐牌留喺度先，遲啲睇下有冇第啲嘢想加)，
**just one 唔該 at the end of your order is enough.
**好唔好？( you are a customer giving instruction to your waitress, asking her " is that alright " at the end make you sound timid.
B: 係, (repeat his order back to him to confirm there's no mistake, we call it 應單 the customer would confirm there's no mistake)
B: 唔該，( that should be the end of this dishes ordering conversation)
If the waitress wanted to assure the customer that his order will come shortly she would say:
請你坐喺度等一下，你叫嘅野好快就到(please wait here in your seat for a little while, the food you ordered will be here soon)
** 阿姐 is also a popular term of addressing a woman whom, you don't know, it can replace 小姐 in your example pargraph,
A: 喂小姐，唔該！
Hey Miss, excuse me!
Starting a greeting with 喂 is quite rude,
Better just : A: 小姐，唔該！
if you wanted to say 喂 because you are trying to get her attention, when she's standing far away from you, you can say, Hi！嗰便嗰位小姐，唔該！( Hi, the lady over there, please! )
B: 先生，你好你好！你想愛乜？
Hello, Mister! What would you like?
You really like to use 愛 instead of 要，don't you?
*要 is far more common than 愛 when you want to say "want"
Anyway, a typical dialog is more like : 係！ 請問呢位先生想點啲乜野呢？ (yes sir, what would you like to order?)
A: 我想愛一碗雲呑麵，加底，唔該。兩杯/盃(Which one is proper?)熱奶茶，唔該。同埋...而家都OK喇。留下張單(What's the proper way to say menu?)喺度先，遲啲/後嚟(Which one is used more for later?)睇下有冇第啲嘢想食/order(食 vs order)，好唔好？
I want one bowl of wonton noodles, increased portions, please. Two cups of hot milk tea, please. And...Right now everything seems okay. How about leaving the menu here first, and later on I'll see if there anything else I want to eat/order, okay?
加底 mean extra base( noodle in this case), if you want bigger portions that include more topping (wontons in this case), you can pick "large" size if the menu listed different size.
A: 我想愛一碗雲呑麵，加底，兩杯/盃(Which one is proper?)熱奶茶，唔該。同埋...而家都OK喇。份餐牌留喺度先，遲啲睇下有冇第啲嘢想加)，
**just one 唔該 at the end of your order is enough.
**好唔好？( you are a customer giving instruction to your waitress, asking her " is that alright " at the end make you sound timid.
B: 係, (repeat his order back to him to confirm there's no mistake, we call it 應單 the customer would confirm there's no mistake)
B: 唔該，( that should be the end of this dishes ordering conversation)
If the waitress wanted to assure the customer that his order will come shortly she would say:
請你坐喺度等一下，你叫嘅野好快就到(please wait here in your seat for a little while, the food you ordered will be here soon)
** 阿姐 is also a popular term of addressing a woman whom, you don't know, it can replace 小姐 in your example pargraph,