No. Micromax Bharat 1 (2018) V409 does not have the OTG support.
Yes, Micromax Bharat 1 (2018) V409 does have the pre-installed WhatsApp application.
Yes, Micromax Bharat 1 (2018) - known as Micromax V409 does have the Kannada language support.
Yes, you can browse Facebook easily with the help of pre-installed Opera browser of Micromax Bharat 1.
Yes, Micromax V409 (Bharat 1 2018) does have the support for the Marathi language. You can change the entire phone's language to the Marathi. You can store contacts, write messages in Marathi, too.