Adding features to a site chosen by me of WordPress

what I need, is if after choosing a WordPress theme, for example a blog, it is possible to add additional functions as in the following description: 1. the possibility to the admin to create one or more pages, in which you/he/she must be possible to introduce images or relative icons to events or objects, with the relative descriptions. 2. the unregistered user who clicks on the image with the intent to join, will have the obligation to register on the site to be able to join the event or object. 3. Every event or object you/he/she must foresee a counter that underlines the number of subjects that you/they have stuck to such event or object. 4. For each event or object, it should be possible to send mail to members, to communicate the situation of the event or object. Both individually and in groups, obviously for the members of every single event or object. 5. When the registered, reenters in the site, after having effected the login and clicca on the event or object on which you/he/she was previously enrolled, you/he/she should open the personal page, in which the state is visualized general event or object to which you/he/she is enrolled: from the date on which the event or object was registered, to the e-mails that occurred for this event or object, the image of the event or object. This page / summary pages should also be accessible through the access to her account.