Here are the card counts and likelihood of getting each type of card: 4 Rares and 3 mythic rares with the serialized double rainbow Ravnica City treatment There are 250 copies of each serialized rare and mythic rare card for a total of 1,750 total serialized cards in Collector Boosters
Watermark: Water Tribe Illustrated by Tetsuko Standard Legal Alchemy Legal Pioneer Legal Historic Legal Modern Legal Brawl Legal Legacy Legal Comp
You get to open two booster packs for free each day, though obviously you're then able to buy plenty more
You can use external tools or extensions to track how many copies of a card you own during a draft, or manually track it if you know which specific cards you're on the lookout for
When looking for valuable Chinese Pikachu cards, prioritize promo cards, cards with unique artwork, and always consider their graded condition
It might surprise some people how often they discard the only two cards in their hand, only to draw land, but the card definitely can be swingy