Simple Questions from a Newbie..thanx Merry xmas

im sorry if i sound like i have no clue what im talkin about but im just very curious at this time....

1. in a profitable sense is a shoe with more or less decks better to play??

2. ive seen books online about how to win at online blackjack.. but is this possible? i mean how do you know they arent screwin you..its like the dealer and cards are rite in front of you...so how can you know for sure it is legit?

thanx agian