That was Larry the bully who turned out to be gay. I don't know why the Wiki didn't have him listed as being in The Wish episode.
Xander didn't "poof" from Buffy's crossbow arrow because it pierced his shoulder but not his heart.
To turn a human into a vampire, a vampire drains most of the human's blood thru a bite then feeds the human some of his/her vampire blood. A bite alone isn't enough in the Buffy universe. In a few vampire stories a bite may be enough but not in most vampire stories including Buffy.
The Master from season one was never given any another name. Apparently in a season one script he had a name but it was never actually used on the show.