Video Poker is the arcade card game with genuine strategy behind it: five cards dealt, you choose which to hold, the rest are replaced, and you're paid according to the hand you end with.
Unlike a slot machine, every deal has a mathematically correct set of cards to hold. Learning those decisions is a real skill, and it's why video poker has a following that slots never developed. Credits here are virtual — nothing to deposit and nothing to withdraw.
Yes — every deal has a mathematically optimal set of cards to hold, which is what distinguishes it from a slot machine where outcomes are pure chance.
No — this is a free game with virtual credits. There's nothing to deposit and nothing to cash out.
A royal flush — ten through ace in one suit — which pays far more than anything else and is worth drawing toward from three cards.