No, you quicken it without getting slower.
When a sorcerer (or other spontaneous caster) uses any metamagic feat, it changes the spell's casting time to one full round. That means Quickening is useless for sorcerers. Song of Celerity is not subject to that effect, so a sorcerer/bladesinger can use it to quicken his spells.
Quickening a spell does not remove its components. The caster must still speak for verbal components, gesture for somatic components, and so on. He just does it faster.
If you want to cast a normal spell as a free action without suffering arcane spell failure, you must use both Quicken Spell and Still Spell.