Samsung B310 comes with 800 mAh battery. But it is very efficient. You do not require to charge the phone for almost 3 days with moderate usage.
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, you can use memory card in this phone.
Yes, but you have to use sim card adapters to make them work.
No. Samsung Guru series phones do not have this option.