7/1/2013 Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesn’t provide any additional benefit.
You are correct: you will not win. The Scarab God states the tokens are Zombies instead of its original creature type
from the card rulings.
7/14/2017 The token is a Zombie instead of its other types (unlike Zombies created by an eternalize ability) and is black instead of its other colors. Its power and toughness are 4/4. These are copiable values of the token that other effects may copy.
From the Card Rulings:
7/1/2013 Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesn’t provide any additional benefit.
from the card rulings.
Just posted a few minutes ago.
The Artwork, from Terese Nielsen, looks beautiful.