RE: Batteries running-in and swollen batteries
My experience has been that some brand new packs are defective on arrival. The best way to detect is to fast charge the pack as it will be charged later on. A pack with at least one cell super slow to take charge is defective and should be returned.
On controlling of swelling which is inevitable, it seems a good practice is to avoid over-discharge (e.g., discharge it too fast, at a higher rate), for the packs at hand. Use of a low pitched prop (e.g., 20.5X13 instead of 20.5X15), flying the plane slow, and proper throttle management do help.