I think there are two key reasons to add or not to add 色:
色 adds formality especially for shorter (1~2 characters) color words.
色 can be added or omitted for the prosody of the sentence.
I found a good article on this very topic: 对外汉语教学中汉语颜色词的构成分析. A few points taken from/inspired by the article:
色 is necessary if the word itself is not a color, such as ...
When I was first learning Chinese, we were using the New Practical Chinese Reader series of books. In them:
Dialogues and vocabulary are presented with both characters and pinyin.
You were only expected to memorize a subset of the characters used in a given chapter (e.g., in the first dialogue, you only had to learn how to write 你, 好, and 吗 or something ...
Probably you should check out the official website and see if they impose any regulation on preparatory materials, I guess they don't.
I assume, to be fair, you won't be able to advertise your app as 'approved', 'official' or 'everything you need to know'. After all, the vocab lists they provide are not sufficient for the test, at least in some levels. ...
I am not familiar with AP Chinese curriculum but I would recommend go by China's HSK.
HSK is designed for non-native speakers and is administered by an agency of Ministry of Education.
If you adapted the HSK, you might lower your cost of authorisation. Even though I don't have the actual number, you could tell from the exam fees.
HSK is harder ...
May this help you: As a member from a non-english spoken country, we start to learn english by words, not by phonetic transcription, because the phonetic transcription is less funny but more difficult to remember. in my opinion, you should start with characters.
成语接龙 is a game for fun, which is used for opening our mind. You don't need to make sure the first Chinese character of every 成语 should be same to last end character, only same pronunciation is enough. Try your best to figure out 成语 which help you improve your mind and memory.