Yes, Micromax Bharat 1 does have the removable 1800 mAh battery.
Yes, Micromax Bharat 1 V409 does support the Gujarati language.
No. Micromax Bharat 1 (2018) V409 does not have the OTG support.
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.