How to make Shopify webshop multilingual?

We googled this problem to find out most new and trendy, relaible and feisible solution but became more comfused so came here with big hope.

We have a webshop based on Shopify and want to make it multilingual. We tried some apps but they didn't give us the result as we want. So, we think, we need to make it manually. We have this criteria:

1. Most of our pages are static. We are using Shopify for every thing but are ready to change and use API only for the ecommerce services, if needed.
2. Our non-technical marketing personnel has to add his contents for all language without much hassle. Possibly, adding content in one place and it goes to relavent language pages.
3. Our Spanish domain is es.example.com, German is de.example.com ..... When our visiter type www.example.com in his browser, we want to redirect our visitors to local domain based on their IP location using Java Script. But also give option to choose the language.

We know for some members, this may not be problem asked in this platform, but we believe other members will definately understand our dilemma.