There are 2 Japanese "alphabets" or phonetic systems; hiragana & katakana. Both systems allow easier reading of kanji (the Chinese characters) with set syllables whether they be a consonant and vowel combo or a vowel alone (never a solitary consonant). Hiragana is used in general for everyday Japanese words and katakana is normally used for foreign or loan words. I don't know what they "translate" to in meaning like what the "hira" and "kata" mean. I looked up katakana and I think it just means "fragmented" kana while hira is script. I would guess their literal meaning has to do with how their styled. Hope that helped. I studied Japanese (the hard way) for a few years.

That's a very big question, but you can easily find very good sources online to help you with the answers.