Confused about Kanji words pronounciation

[Bizy]

Hello minna-san,
I am going to change my full name to Japanese so I need some clarification about when names are written in particular kanji. I personally wish I didn't have to write my name in kanji but in kana instead because I find it problematic. If a word has both a kunyomi and onyomi readings, how does one know (someone else reading my name) how to pronounce it?
I can give an example with a different word:
弓 is "ゆみ" and "きゅう" so how will it be pronounced in general by Japanese speakers? I am confused about this. Also, what if the word has additional kunyomi or onyomi readings? I heard it depends on the context in sentences but what if the word is by itself, like above?
Is it uncommon to write one's name and last name in kana in Japan? Can I do that instead? I just want it to be read as the way I want it (kunyomi) and not onyomi so I would like to make sure about what I am going to use.
____
Another question about something I mentioned:
The "きゅう" / kyuu above for example (or other words that have the romaji ending with additional vowel. Does that have to be written that way? Will it still be correct to write "kyu" instead of "kyuu"? Is there a set rule that it has to be with the double vowels?

Thank you in advance!

 

[SomeCallMeChris]

Foreigners names are usually written in katakana, even if those names are Japanese in derivation (e.g., Americans of Japanese descent.) The names of Japanese and Chinese persons are essentially always written in kanji. (Kana given names on children's personal items being about the only exception. Family names are never written in kana except to provide the reading of the kanji.)

There are literally no rules about how kanji can be matched to pronunciation. There are common names, that everyone knows how they are commonly pronounced (but they often have alternate pronunciations too), and there are characters commonly used in names that usually have one or two commonly used pronunciations (sometimes the same ones as in words, sometimes a special 'name reading').

However, ultimately, the new parents (or someone changing their name) can put down any of the 2500ish kanji that are allowed by the government, in any order, and specify them as pronounced with any reading.

 

[JimmySeal]

You're in a situation where you have to change your name to kanji and you have only a minimal understanding of how kanji work? How did you get into this situation?

 

[Toritoribe]

Another question about something I mentioned:
The "きゅう" / kyuu above for example (or other words that have the romaji ending with additional vowel. Does that have to be written that way? Will it still be correct to write "kyu" instead of "kyuu"? Is there a set rule that it has to be with the double vowels?

Not double vowel but long vowel. You asked the same question and already got the answer 11 years ago.
What is the difference?... | Japan Forum

Also, you asked the similar questions repeatedly. Now I'm wondering if you really want to know it or you are just trolling...

 

[johnnyG]

Once upon a time, and you need to think of your grandmother or more likely your great-grandmother here, names for females were written in katakana. You can sometimes see this in funeral notices.

These days, I can recall seeing (and would not be too surprised by) a woman's given name being written in hiragana, but never a boy's. This is based on seeing a lot of student name lists over the years.

For family names, sometimes you just have to know. E.g., 新村 could be either 'niimura' or 'shimmura'. For the most part, tho, there is just one reading.