Yes, yes, and yes. Looks like you've got the basics down!
Any other newby i'd suggest that the 'sourness' is just dry cider taste since sensory descriptions are hard to convey through text but since you've got two other similar batches going which taste 'normal' then it may be time for damage control. Killing off the offending acetobacteria via batch pasteurization will stop the cider to vinegar reaction.
Be aware thought that when bottling a still cider in bottles it is best to minimize the air in the neck via either CO2 purging (if you have a kegging system) or by filling up as close to the cap as possible. This minimizes the chance of infectious bacteria spoiling your cider in bottle. Traditionally carbed ciders are more resistant to this as the carbonation decreases the pH of the cider making it more hostile to infection.