1993 includes Magic 's earliest printings, such as Alpha, Beta, Unlimited, and so on, and some of those cards can be extremely valuable depending on the card, condition, edition, and whether it is tournament legal
Cards like Purphoros, God of the Forge can burn opponents to death even without attacking, which is vital if the board state is stalled
Of course, this requires you have a permanent of the same type to sacrifice yourself, but that's not a huge cost looking at the prevalence of cards like Fable of the Mirror-Breaker, Experimental Synthesizer, and treasure token generators
A deck like Arceus VSTAR / Flying Pikachu VMAX [Celebrations] might only have Bibarel [Brilliant Stars] that they might attack
Yes, you can specify the condition of each card (Near Mint, Lightly Played, etc.) which affects the accurate valuation of your collection
They are only "sheen" holos, meaning they have no other effects