Yes! Currently it is a premium feature and can be done by clicking the button with the 3 vertical dots next to each card.
Not yet, but this is something that is being worked on.
In most cases, you are probably referring to the Unlimited variant of the card which happens to have a Rare Holo rarity. If there are multiple variants with different holographic patterns, the original one will be listed as Unlimited, the parallel variant as Reverse Holo and the special or later released one as e.g., Cosmos Holo, Cracked Ice Holo or Water Web Holo.
However, if you still think a card variant is missing, please report it to us. Thanks!
The current information listed on the site about premium is somewhat outdated. We plan on having multiple subscriptions that will range from $2 to $5 in price a month, billed annually. Basic features will always remain free to use.
There is no specific date planned, but we are able to successfully fetch the prices from TCGplayer at this point. It still needs to be integrated into site itself and remains a high priority feature.
Maybe sometime in the future. It's not something we have planned, but we can look into it.