Yes, you can use Sony MBH20 with Gionee A1 easily.
Yes, you can use Sony MBH20 with micromax mobile phone.
No. Sony MBH20 do not have volume control button. You cannot increase or decrease call volume but you can use your mobile phone's call volume control button for the same.
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.