THXkid No and Yes, you can modify the E129 battery by removing the 2 small pointed tips on the top of the battery, then the battery will slide further down and make connection, they are smaller batteries so I would say you will loose about 20% of your flight time. Not ideal solution but if you can find any K127 batteries, better than loosing the use of the K127.

THXkid Or buy the batts for the E129, modify them by sanding off the click tips on them so they slide all the way down, you will loose some flight time, they are smaller batteries.

THXkid vibration can be bent shaft, bad head, loose or too tight of main blade, out of balance blade or bad gyro on flight board.

THXkid Yes all parts can be bought at the RC ERA web site, I have checked them out, all parts are available.

THXkid all controllers by RC ERA can be changed to mode 1 or mode 2, hold landing button then switch on power choose which mode to band then its set, turn off, turn back on and you have it set to that mode, can be switched back and forth any time.

THXkid No either can be set on the controller to mode 1 or Mode 2 only.

THXkid You can switch any of the controller to either mode 1 or mode 2, hold landing button then switch on and choose mode 1 or mode 2, turn off, now its set for that mode.

THXkid RC ERA web site sells very part for all their helos there.