Can miraculous holders be Akumatized?

Miraculous holders can continue owning their Miraculouses to any age as long as they're using them and their bodies are capable. Miraculous holders can be akumatized, as revealed in "Queen Wasp".

Did Tikki get Akumatized?

The next day, they arrived at Andre's ice cream stand and when Tikki got a taste she found it delicious. In "Sapotis", Tikki came with Marinette who joined Alya for a sleepover at her house until Alya's younger twin sisters got akumatized into the Sapotis causing a ruckus in the house and then escaped into the city.

Can Kwamis sense other Kwamis?

All of the Kwamis know each other and journeyed across the universe for eons.

Is Duusu a girl?

Previously, it was split and the French and English called Duusu a she, others called the kwami a he. So now, it is official that Duusu is a he, but what do you say to this? Tikki: (gasps; she and Plagg fly over to Sass) We won't make it, Sass.