do basic lands count against sideboard total?
You cannot swap in basic lands during a match or tournament in constructed unless they are part of your sideboard.

The fetch lands are in the deck to filter the lands as soon as possible. They only fetch forests in this deck. When you fetch a forest, there are less cards in your deck, so the chance of drawing a card you want (not a land usually) is bigger.

The black and blue cards in the sideboard are traps, they can be played for free in certain circumstances, so therefore you need no black or blue mana.