1. As far as I know, Robert and Mitori were confirmed straight in canon. It’s kept on SH.
2. She has! Aside from Flake, she’s shown it to Dillaw [Doesnt enjoy it], Pinku [Does not understand it], Alexander [Doesnt like it.], and Joy/Jorwasse [Did like it].
3. The main trio are surprisingly varied. Most of their off-time is spent in the base. Robert would most likely walk around, do some target practice, or play a game. Mitori would be more bound to her room, reading, training, or just keeping an eye on Robert. Shiro is less consistent. Sometimes she’s just joining the others on their antics, others, she goes out and about incognito to just fool around.
The Trio very much do dread it. Even if Ben doesn’t have the authority to fire them in SH, they do fear what he CAN do.