Sony MBH20 has average talk time of up to 8 hours. So, you can use it for almost 2 days talk time.
Yes, You can use Sony MBH20 with Nokia 3310.
Yes, you can.
Sony MBH20 comes with Sony battery only. As per company, it offers up to 100 hours of standby time and about 7 hours of talk time.
Yes, Sony MBH20 does have call ending button also.