I've done that pattern more times than I care to count. It's a really good pattern and totally worth the money. My Mother asks for a pair every year for Christmas and she wears hers everyday but only inside the house. Her's only last 2-3 months but she is very hard on them.
I've seen the leather soles at specialty yarn stores before but they would probably be just as easy to buy online, I've never used them myself.
I dunno about cork or about wearing them outside.