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.
Yes, Micromax Bharat 1 (2018) V409 does have the pre-installed WhatsApp application.
Yes, Micromax Bharat 1 does have the removable 1800 mAh battery.
Yes, You can use Micromax Bharat 1 V409 has a wifi hotspot. You can use your 4G SIM card and can enjoy seamless internet browsing.