To view ACES xml catalog application data in a friendly, human-readable form.
Yes, you need a subscription to the AutoCare vehicle tables (VCdb) in order to use AceViewer. http://www.autocare.org/What-We-Do/Technology/subscriptions/
AceViewer comes in two editions: Standard and Professional. Standard is a low $450 per user (or $1400 unlimited). Professional is $3800 for unlimited users
Yes, it is installed with the trial version and also available separately here.
Download a trial version here. Random applications are skipped and export is limited to the first 100 rows.