Translation:Livia would like a new white dress.
I can't say with any degree of certainty, but here's my shot in the dark...
So in Spanish the general trend is that adjectives come after nouns, however there are notable exceptions, such as numeral quantifiers and words that are more situational, or personal. An example might be a new bike. It may be new to me, so I would put the adjective first, then the noun in Spanish. However, if it was freshly made straight off the conveyer belt, it might be a "bike new," as per the Spanish standard.
Basically, adjectives that are objective come after the noun (even if it's technically an opinion...don't think about it too hard...) and ones that may change based on the speaker's relationship with the noun generally tend to come first.
My guess is that this may apply to Latin as well. Hope this helps!
Answer to your first question: the word “candidam“ comes after the noun “stolam“ like most adjectives, but they are placed before the noun if they indicate a distinguishing characteristic or are measure, degree (comparative and superlative) and number determinations. E.g. old, new, big, small, one, two. Answer to your second question: Yes, exactly how you hear the words. In the same order. If you hear X Y but you would write Y X, it would be wrong.