Answer 1

I am a civil engineer too bro and 24 years old. There is no age for coding you just have to be consistent and work hard. And regarding java or JavaScript first let me tell you both have no connection with each other. Since you want to earn money you have to make up your mind, you do want to earn by making a website or making an app(android or ios). That will determine the language you need to target. If you want be in the app world then there is no need to touch JavaScript. For android you need to learn basic java and jump into android programming and for ios you need to learn swift. If you want website to be the source of income then you need to start with HTML then move to CSS and JavaScript. Decide your project and choose your language.

Answer 2

Bear in mind: Java is not similar at all with JavaScript. One is used for creating dynamic web pages (JavaScript) and the other for Object Oriented programming. If you want to learn JavaScript learn HTML and CSS first.
No you arent too old to learn to code.

Answer 3

Why don't you try some of the courses, and see for yourself what you like?