XBMC 15.3 or 16.3?

I am using Minix Neo U1. It shows XBMC 15.3. There is no option in XBMC to check for upgrades (or I could not find one). I saw somewhere in this forum people talking about XBMC 16.3
Q1 - How do I know which version is best for me? Though presently I am not having any issues with 15.3 but do I have to upgrade?

Q2 - How do I upgrade my XBMC to 16.3?

Thanks