If you're considering grading valuable singles pulled from your boxes, the Pokmon Secret Rare grading guide covers the evaluation framework - applicable to assessing whether any high-rarity TCG card justifies grading costs
Equip only appears on artifacts with the Equipment subtype, most of which are colorless
Sliver Queen Mostly Undisputed Queen of the Slivers since 1998
And do keep in mind, you will need a deck box designed to hold 100+ double-sleeved cards
The first is a triggered ability: "When this permanent enters the battlefield, target player may search their library for a card named [name], reveal it, put it into their hand, then shuffle their library." (2018-06-08) Note that the target player searches their library (which may be affected by effects such as that of Stranglehold) and that the card they find is revealed, even though these words aren't included in the ability's reminder text
There are other factors that can make a card valuable aside from what symbol is printed on it
