Hi Marco,
Thanks for contacting us!
Good question. While there is no built-in option to force a minimum number of tickets to be selected for an event, there is a snippet you could add to your functions.php file to do that. Please refer to this thread for the details.
Once the number has been selected, Event Tickets Plus will ask the user to provide the registration details for each ticket just the way you are looking for.
Does this help answer your question? Please let me know. 🙂
Cheers!
Geoff