Adding RTL to WP Classifieds theme and switching between languages

I have a recently installed WP Classifieds ads theme website with some custom works. The custom works are in Child theme. Currently, its in English and now I want add RTL language with a specific font to RTL language. Languages can be switched between English and RTL language and with switch, everything must corresponds to the change. All English posts can be aligned to English and RTL posts should properly follow RTL rules. Custom works should be seen and available in both languages. Must be compatible with ALL devices. Language and fonts must be automatically loaded on all devices. All changes must be done in Child theme. With theme updates, all custom works must be intact. For serious developers only. Prices must be final, no placeholding bids are acceptable.