I believe you speak/understand Italian, so please don't ask me a word-by-word translation.
Longo is considered "club trained" because Inter owned his sporting rights from the 2009-10 season (when he joined the Club) to the 2012-13 one (when he turned 21). It doesn't matter if he went on loan during that time because he always remained under Inter's control. Conversely, Icardi is not considered "association trained" because, even though he spent three full seasons between Sampdoria and Inter during his formative years, the first one he did as a loanee from Barcelona and therefore doesn't count. Anyway, Longo has just been signed by Deportivo La Coruña, so he's not our problem any more.
You're right about Esposito (except he will become "club trained" at the end of this season). It doesn't really change anything, though, considering he will fit the "under 22" criteria for another five years.
Lastly, I made the table with Serie A rules in mind. With regards to Champions League, we would currently be able to register 26 out of the 27 players on the roster (17 free + 2 club trained + 4 association trained + 3 b-list). The club probably intends to address the problem by getting rid of one expendable player (Dalbert?) and replacining him with one fitting the "club trained" criteria (Biraghi?). Other than that, we will operate on a "one out, one in" basis.