🃏Draw a card from a properly shuffled deck.

Not within a single draw. The deck is shuffled and the cards are dealt off the top, so ten cards means ten different cards, exactly as with a physical deck. Press draw again and the deck is reshuffled from all 52, so a card from the previous draw can certainly reappear — each draw is a fresh deck, not a continuing one.

Fifty-two: thirteen ranks in each of four suits. Turn on jokers and it is 54. That is the standard international deck; games that strip it down — piquet at 32 cards, some European games at 40 — are not covered here, though drawing repeatedly and ignoring the cards you do not want gets you there in a pinch.

One in 52, or 1.92%, from a full deck. An ace of any suit is 4 in 52, or 7.7%; a heart is 13 in 52, or 25%; a face card is 12 in 52, or 23.1%. With jokers included every one of those figures drops by about 4%, since the same number of favourable cards is spread over 54.

Better than most real ones. Seven riffle shuffles are needed to properly randomise a physical deck, and almost nobody does seven — which is why card players can read patterns in a badly shuffled deck. Fisher–Yates with a cryptographic source produces a uniformly random ordering in a single pass, with no clumping left over from the previous hand.

For games, yes — it is a deck you cannot lose under the sofa. For magic, the honest answer is that a screen removes most of what makes a card trick work, since the audience cannot handle the deck or verify anything. It is more useful on the performer’s side, as a way to generate a genuinely unpredictable target card for practice.

No. The shuffle happens in the page, the cards are displayed, and nothing is stored or sent. Reloading gives you a fresh deck with no memory of what came before, and there is no way to recover a previous draw — so if the result matters to someone else, screenshot it rather than trusting the page to remember.