Question about the "eraser" tool (Gimp 2.10)

Hello.

When I use the eraser it erases an area using a "gradient" intensity. Basically, the further the zone is from the cursor, the less it fades. How to make it equal across the whole area?

Another question: how can I make the eraser erase only one pixel (even if I set the size to 1 px, the sone erases on 2 or 3 pixels located around it)?