Wow. Nested question. Based on my past experiences:
1. Focus on the one (or two) things that a good number of people are keen on (e.g. Adaptive LED Headlamps)
2. Use that "assured" volume to discuss with the OEM distributor and/or local distributor - this should be done by at least 2 representatives
3. Once price is negotiated, collect 50%-75% payment from all parties who have cited interest to facilitate ordering - if paid volume is not met, then group buy is cancelled
4. Place order and share shipping information (tracking ID) with all participants
5. Upon delivery, all participants to arrange with the (2) designated representatives or local distributor to collect their order
Do note that
sometimes the representatives do enjoy perks or additional benefits as they are assuming a certain amount of risk for paying up the balance in advance to bring the order in. So don't be upset but volunteer to be a rep and put skin in the game if you want those perks!