I have always thought that romaji should never be used in the early stages of learning Japanese, but furigana still is not enough.
ʤʌst θɪŋk, International Phonetic Alphabet could sove all problems at once, examples:
ラーメン ɽaːmɛɴ
ふとん ɸɯtoɴ
No, it would just make it more confusing. There are many ways to pronounce a word (consider fu) and IPA differentiates it. Romaji would be superior to that.
Does IPA have tones?
yes
>>2
what fu are you talking about
fufufu
hu > fu !