They don't unless the female partner has thrush. Then they get it in exactly the same way as getting thrush by any other means. It is a fungal infection that can affect any part of the body but is...
Yes you can get thrush from oral sex.
Yes it can...See link below
Thrush is a fungal infection of the tongue. So if there is a fungal infection on the male genitals, then yes, it is possible.(see related link)
Yes you can get it it if it is not healed well.