Yes he did attend the school although he was unable to attend most of the time as he had to work. Maybe they become acquainted when Joni starts pursuing Sloth and with the constant visits (and the addition of snacks), seeing as how Joni meant no harm maybe Ash invites Joni to visit Sloth in person and from that she invites you or something?

The part of his face covered? It's a mouth and nose thing, a bit like those flu masks people wore but I like the design of the one I put up. He also sometimes wears a sort of gas mask which specifically only covers his mouth and noise (showing parts of his injuries) unlike the 'flu mask' which it's prime function is to cover his cuts and stitches entirely. 
[img]http://ibin.co/1IlIAIYrCTxk[/img]
Like this mask but smaller.