Tribe-Infecting Virus is enabled by the ritual searchers much in the same way that Back to Square One, Raigeki Break, and Phoenix Wing Wind Blast are
Auriok Transfixer Auriok Transfixer attacks opposing artifacts rather than creatures
Not background necessarily, but some other line of text that says something along the lines of Whenever you sacrifice a Treasure token, give a creature a +1/+1 counter and trample until end of turn. That would make it a lot more interesting and powerful, but I suppose not every card needs to be great
The surface includes everything visible on the front and back of the card: scratches, print lines, stains, dents, creases, and even the card's original gloss
While there are lots of cards that do similar exile-then-steal effects nowadays, Etali is still one of the best to ever do it, and is certainly the best monored option for anyone hoping to pull this strategy off