For sigil of the storm, if I conquer, do I get the energy and power cost for floating it for that turn?

No — the recycle itself gives you nothing. Sigil of the Storm just instructs you to recycle a rune; that doesn't add Power to your pool (Rule 164.2.b / FAQ 11774).

You can still float that rune's Energy: tap it for [1] Energy first (this can't be responded to), then recycle the same rune to satisfy Sigil — the Energy stays in your pool until end of turn. You just can't get Power from that same recycle, since Power only comes from activating a rune's own "Recycle this: Add [C]" ability, which consumes it.