When a judge vacates a judgement he/she makes the previous judgement legally void. This usually occurs when a judgement has been appealed and the appellate court decides to overturn the original ruling.
In police jargon, a case is 'closed' when it is solved either by arrest, or "by other means" (i.e.: when the perpetrator is known beyond a reasonable doubt but cannot be prosecuted - by admission -...
The concept of waiver in a criminal case means that the defendant voluntarily gives up certain rights. The defendant has a number of rights: to remain silent, to a jury trial, to cross examine...
The "disposition" of a criminal case is it's outcome. For example: acquittal, conviction, dismissal, etc. Not disposed means there has been no final court decision.