1) I wanted to know, what is the maximum length of hair which will be considered "Short" in Islam, i.e. suitable to be wiped on during wudhu

2) And is it permissible to wipe ones root/scalp I’m backwards direction, i.e. from the forehead to the direction of back of head?

by

1) If the hair from the upper head area (where you wipe in wudhu) extends out of that area down to the face, then one must wipe the root of the hair or the scalp. So if the hair extends from that area out onto the forehead or face, then you should wipe on the root/scalp.

Therefore:

A) I mean that it reaches the forehead area, not that it covers the whole forehead area. So if the hair from the middle top of the head is long enough to reach down to the forehead (so it’s like 4-6 inches long) then wipe the root/scalp.

B) If the hair is long and taken back by a headband, you still would need to wipe on the root/scalp

2) Yes you can wipe in backwards direction