Rules Compendium 194. It's specifically a limit on free action attacks, not all free actions. And it is only to specifically making an attack as a free action, so for example a warlord can use Knight's Move to give the rogue a free action Move Action that they can downgrade to a Mior action attack, and because it wasn't "make an attack as a free action" it doesn't count against it. And yes, you can take free actions after charging, spending an AP is a free action.