1) If I am right, Ho wrote the memo in the prison after he was arrested in Hong Kong by the British police. I am just starting to learn Mandarin, so am not so as good as that I can read the text (I used google for translation

).
Nor I am an expert in Chinese or Vietnamese writing history. Indeed we used Chinese writings for nearly 2 millenniums until the French conquered Vietnam and made French to an official language at the end of 1900´s.
2) For us, it is much more easier to use latin alphabets for learning Vietnamese. Before that we had to master Mandarin, then we learnt the chinese-vietnamese version of Chu Nom. Chu means writing character, Nom means Nam (south).
Vietnamese language - Wikipedia, the free encyclopedia
"
For most of its history, the entity now known as Vietnam used
written classical Chinese. In the 13th century, however, the country invented Chữ nôm, a writing system making use of
Chinese characters with phonetic elements in order to better suit the tones associated with the Vietnamese language. Chữ nôm proved to be much more efficient than classical Chinese characters and consequently was used extensively in the 17th and 18th centuries for poetry and literature.
"
A video with Vietnamese and classical chinese-vietnamese characters (chu nom). Check if you can read them!