Am installing amp into my escort gti, few questions please

1) i know about removing wheel and carpet behind this, but someone mentioned the carpet is held in by "star shaped screws" what size are they?

2) where do i ground the amp (its going into the boot)?

3) can i mount amp on top of sub box?

4) Any advice on running cables to boot ( i know to go power one side etc), do i need to remove panels or is there an easy way through?

thank you