Hi
I couldn't answer your questions with which is easiest, as it will greatly depend on the gymnast. If you have a gymnast who is good at pirouttes and lacks shoulder flexibility it might be worth the pirouette entry. Personally i would rather teach it from a jam if the gymnast has the facility for it...as that can later be use for a Takamoto, which well is definitely the skill of choice in the COP at the moment. It is assumed that the gymnast can already to a hecht tap giant.
The giant itself is trained similarly to training a front giant. First part is the bail.. This can be taught by using this drill:
1- Setup a mini tramp with a low bar (HB about thigh height is best). Have the gymnast hold the bar in a el-grip. From a couple of bounces the gymnast bouces to that pike you mentioned (With your help). You stop him at that position, and they open up to a handstand and fall to their back onto a super soft mat. You might want to at the start slow down their fall, or make the angle of the mat a little (rather than flat) to help make the fall more comfortable. A gymnast who cannot hang in a dorsal hang with at least! 165deg angle (absolute lowest in my opinion) should not do it from a jam, and you should make them fall onto a raised surface above the bar, otherwise shoulder will be punished.
Once they can do well you can also work a front flyaway from el-grip from a bail. Spotted at first of course.. you are working here on 2 skills - timer/prep for a Balabanov from el-grip, and also on the tap. Once they understand the tap (which is the same as the hecth tap for a front giant) than you can spot them for the full skill. If they have learned the tap well.. they can either tap and pike it into a Russian giant (which you have done already on the bar drill) (this = a C). or the can tap and ride it like a front giant (B).. once again this part is wrist and shoulder flexibility dependent. I would go straight into the pike action as you have already worked this with the drill above.
You should spend time preping the gymnast in el-grip before doing stuff in el-grip. Things like handstand on single rail in el-grip, pirouttes into el-grip and out of el-grip. swings in el-grip (small), beat swings in el-grip etc.. To strengthen the wrists and shoulders. This is important in my opinion as otherwise soon after you start working in el-grip your gymnast if not naturally flexible in that position will start to complain of wrist issues and shoulder issues.
You should also do rotator cuff exercises as injury prevention (which is also inportant for giant inlocates and dislocates)