hello,
Would like to build a wordpress website and here are my questions:
1) What places can you recommend for getting themes and plugins for wordpress?
Found Sparklewp.com themes for wordpress. Have you ever heard about them before?
2) What are the best WordPress Translation Plugins you know?
3) Advantages of Using Translation Plugins?

WPML.
TranslatePress.
Weglot.
MultilingualPress.
Polylang.
Prisna GWT.
GTranslate.
Lingotek.

Be careful when using third-party themes and plugins, as they can often introduce security vulnerabilities and slow down your website. Sparklewp.com might look shiny, but have you checked their code quality and customer support? As for translation plugins, I've seen many websites struggle with WPML's complexity and Polylang's limitations.

Loco Translate is a decent option, but it's not perfect either. If you want to create a multilingual website, consider using a more robust solution like a custom-built plugin or a dedicated translation platform. Translation plugins can be a quick fix, but they often lack the nuance and flexibility that a custom solution can provide.