No. You cannot use 4g network sim cards. You need to select 2G network for your sim card and then you can use it.
Yes, Samsung Guru Music 2 works with Kannada langauge.
This seems to be some software related issue. You should visit the nearest Samsung authorized service center and get it checked.
Yes, a pair of earphones comes free with Samsung Guru Music 2 as in-the-box accessory.
You can use normal sim card in this phone.