You may tap or untap target creature. Then that creature's controller may pay. If the player does, they may copy this spell and may choose a new target for that copy.
10/4/2004 The decision to tap or untap is made on resolution of the spell (and of each copy).
10/4/2004 Paying to make Chain Stasis continue is done as part of the resolution of the spell.
10/4/2004 The copy is a spell, so it can be targeted by other spells and abilities that target a spell.
10/4/2004 The player putting the copy spell on the stack controls that spell.
10/4/2004 The spell copy has all the text and can result in itself being copied.