Yes, it will be supported.
Yes, it will be supported.
This product page suggests compatibility with older chips such as the i7 6700 without a K. It seems to point toward a more budget-friendly upgrade option for your sister's PC, especially since her motherboard is nearing replacement and she has issues with USB ports.
Only compatible with 8th and 9th generation processors. It's unclear which chipset works for 6th generation, but you might be able to locate it through some investigation.
Most reputable motherboard makers provide a selection of compatible CPUs for their boards. You can find details here: https://www.asus.com/us/Motherboards/TUF...pDesk_CPU/ i5/i7 6*** isn't included.