>>1826953
>traits
You can add any number of traits you wish, but it's better to know what they do beforehand. Add too many, and it'll cause conflicts with the game's AI. The AA2 page in the Hgames Wiki has a good description of what each trait does.
For starters, I'd recommend around 2-4 traits.
>preferences
These affect H compatibility gain and unlocks more lines during H. You can add as many as you wish to your character without worry of conflicts.
>modules
Like traits, you need to know what each module does before you add too many, or else they'll cause conflicts with the game's AI. Unlike traits, however, modules aren't really necessary, so it's actually fine not to put in modules especially if you're just starting out.
>>1827106
Each character can only have four base outfits: Uniform, Sports, Swimsuit and Club. The Club outfit is static, unfortunately. You can, however, use certain style-changing modules to bypass this limit.
>>1827099
Styles are kind of like alternate skins for a character. They're most commonly used with modules to bypass the four-outfit limit a character has, like making your character switch to a dress during dates and Sundays. And with enough creativity, you can actually use them to make a character transform into something completely different, like say, making your character transform into a succubus during H, or a Super Saiyan version of themselves when they're angry.