The triggered ability helps ensure you always have a creature to play and such an effect is the lifeblood of many green decks
Yes, the cards you draw will always be lands and yes, no matter how well you shuffle your deck after, you draw another land way too often because variance hates you
Some, usually where the commander is chosen for it's colours rather than it's abilities, may opt not to run them but they are useful in any deck running important creatures
The new way Companion works is to pay (3) to put it into your hand from the sideboard
Like I already said these arent exact numbers, but it should give you some guidance on what your deck needs
The Final Fantasy 10 and Final Fantasy 14 commander decks have had their prices cut to $55 and $55.98, respectively, and the Final Fantasy 6 commander deck's price has dropped all the way down to $49.80