Does Kiryuin Satsuki have any infused Life Fibers? I know that Kiryuin Satsuki was experimented on by her parents to infuse Life Fibers into her.  She was too old at the time of the experiment for it to be successful but she was able to wear either Kamui (albeit to a lesser degree than her properly infused sister). I assumed when watching that she was partially infused but I now have no recollection as to whether that was clearly stated.  The wiki seems to clearly state that only her mother and sister have infused Life Fibers.

Does she have infused Life Fibers to any degree or is she 100% human?
She is 100% human, but she carried artificial finger nails made with Life Fiber (it is more likely to be a hidden weapon rather than an infusion with Life Fibers).

Kiryuin Satsuki waited until the last minute (until Ryuko arrived at Honnouji Academy with Senketsu) to wear Junketsu. And her butler was continuously against the idea of her wearing Junketsu. When after a fight, Satsuki always had physical and mental stress on her body and mind, so she always tries to end fights as quickly as possible when she is wearing Junketsu.