1: Is it possible to make discounts if a customer buys/attends several events? Like if the customer buys for example 4 events in one shopping-action he will get 20% discount. Is that possible?
Not automatically (that would be very difficult to implement), but you can use coupons.
2: Is it possible to group events into packages with special package-prices? Like if I have 10 events that you can attend seperately, then there could be a package of for example 5 events to a special price. Is that possible?
Hmm with a different fee / coupon, but you would have to control that manually (also very difficult to implement technically).
3: Is it possible for the user to sellect several events before he pays?
No, because you always get a unique id per booking (to edit / get the ticket / invoice pay later etc.)
4: Is it possible to assign a user to a specific Joomla usergroup based on the specific event he buys?
No, currently not - have something similar for webinars on my todo-list
5: Is it possible to offer additional products/services to the user when he selects an vent?
Not sure what you mean with that - you can use any HTML you like and set up different fees to offer additional bonuses like lunch etc.
Kind regards,
Yves