Hello
1. Yes. I think it is possible using custom fee fields, see
eventbookingdoc.joomservices.com/basic-s...wn-custom-field-type
. Basically, allow them to choose the options they want and charge them the related fee
2. What's minimum ? How it should work?
3. Yes. You can setup Fixed Expiration Date for that plan and all subscription will be expired on that same date (31/12 in this case)
Regards,
Tuan