1. Multi - language: I have a suggestion for you is that you can use WPML plugin. This plugin can translate your entire site into the different languages that you set up. It is not free so you have to buy it. Theme supports for WPML
WV: Before buying the theme I asked this questions and you never told me that I have to pay for that plugin. I am very disappointed about this.
2. Error with Contact Us Form: Could you provide me the screenshots for this point so that I will give you the correct answer?
WV: Screenshot attached.
3. Subscribe button for Newsletter: It seems that you still do not enter the API key for Mailchimp yet. Pls go to Worldmart > Mailchimp then get the API key for this.
Please provide me your wp account also. I would like to check your site if you have more issues.
WV: I added the the API Key. Screenshot attached.