1.
William! Wiliam is absolutley hideous--it's misspelled and looks illiterate or like a mistake.
2. I adore the nickname
Liam.
Will is also nice.
Willy is slang for "penis", and Bill(y) is SO dated and ugly.
3.
William Oliver is fantastic, but Willam
Oliver is terrible.
William John is a bit boring, but nice.
4.
William? Yes, very well. Willam? No way.
5.
William is a fantastic name!