Yes, JioPhone does support the Marathi language.
Yes, JioPhone does have the alarm and Indian calander, too.
JioPhone has 2.4 Inch QVGA TFT screen display. It has about 167 PPI ratio.
JioPhones comes with 4GB Internal Memory - so just like a normal Android smartphone, you can save as many contacts depending on the free space in your phone. In practial sense, you can store unlimited contacts.