HI there, I will see if I can help you.
嗰處, 嗰度 mean the same thing.
嗰便 is what I considered to be a slang term but it has similar meaning as 嗰處, 嗰度
I also wouldn't use the word , 個 is the appropriate word.
你愛唔愛買花? = Do you love to buy flower?
我愛 = I love to
are these two sentences identical in meaning? I.e. 定係=定?
Both sentences have similar meaning, so you can use both.
I hope this helps you!