Threadhopping with this character - yes/no/it depends? Yes
As long as there is a reason for you to hop in, sure! It might be polite if you message myself and the other person in the tag, though, if it's looking like a closed conversation. ^^
Backtagging with this character - yes/no/it depends? Yes
Absolutely! Life happens. ^.~
If it's an important plot point, I'll try to message you after one week of inactivity to make sure you're still interested in playing it out, otherwise we can just quickly sort out what happens.
Back-dating entries with this character - yes/no/it depends? Yes
I'd like to avoid it, but yes! Anything more than a week might feel stale though, unless it's a really important plot point.
Hugging/kissing/other sort of intimate actions with this character?
Fuu has her heart set on Ferio. If it's anything more than a friendly hug or a kiss to the back of her hand, please give me a heads-up and message me about it.
Punching or causing some other form of physical harm to this character?
Gosh, someone would harm sweet Fuu? I don't mind surprise attacks, but if it's going to be seriously violent please give me a heads-up and message me about it.
Is there anything that should not be mentioned near this character?
It would be best to keep a civil tongue and to moderate topics around her. Otherwise she'll just blush furiously and leave the room, or ...something XD
Is there anything you need us to know about interacting with this character (i.e. special physical features or abilities)?
Fuu can use wind magic, but in Cephiro she was warned to only use it when she needs it. She's assuming the same rule applies here.
Other than that, and her being quite mature for a 14 year old, she's fairly average.
Anything else that was not mentioned above?
I don't mind surprises! I figure not everything has to be planned out before hand. But it's better to ask than to regret later, for sure. Please use your discression.