They need to make a profit reselling the cards, so youre paying for the convenience of instant payment
Theyll fight normally
That is to say if it is turn 7 and you're going last you can tap Temple Bell to draw your eighth card on turn 7 and while this will also give your opponents their eighth card at the same time, it will be during your main phase while everyone else will have to wait for their main phase after yours before they can use any sorcery speed card they may have drawn
If your opponent cant remove it, theyll struggle to survive on your upcoming attack turn
Yes, this ability does synergize with Sail the Azurite Sea or other effects that allow inking a card. But, it does not work with the effect like Measure Me Again from Tipo Growing Son that allows a player to put a card from your hand into your inkwell. Inking a card is a verb and is specifically different from putting a card into your inkwell
Despite a number of reprints, the price is holding high, and its a key card in Legacy thats also played a ton in more competitive EDH decks to stop your opponents doing anything too quickly