Pre-sale use-case

Hello,
I would like to know if this component could meet my use-case ?

1) I would like to be able to send invitations for a specific private event. People could only book the concerned private event
ONLY IF they receive a link by mail. ie : wedding, club membership, pro event ?

This is a core feature of RSVP Pro - you can have events that only invitees can view.

2) if I fill membership lists, is it possible that people who never had access to the site before could be LOGGED ON with the mail link they received and find their profile informations pre-filled (with the ability to modify it) ?
==> I would like to avoid regular Joomla membership registration !

That is an interesting idea - there is an obvious security risk in doing this which is that if the link gets into the wrong hands then full access to the account would be compromised.

How about the alternative approach which is you create the profiles and use a specific pattern for the password e.g. SurnameYearOfBirth e.g. Jones1987 or Smith1961 and include a note to this effect in the invitation message?

You can indeed have profile information in the event registration form and this can be edited during registration BUT this will not change their overall Joomla profile information ONLY the information specific to this event.

3) is it possible to associate users by groups allowing access to events categories ?
ie : a club membership display specific events not showed to public or other groups.

Thanks for your answers
Best regards

Absolutely - you can have events private to specific user groups and even specific registration fields that only some groups can access or group specific pricing or discounts.