Can a Ghost use feats that have a strength score as a prerequisite?

A Ghost has a strength score, but it can only use physical force as long as it is on the ethereal plane. When a Ghost uses its manifestation ability, “it partly enters the Material Plane and becomes visible but incorporeal on the Material Plane.”

As an incorporeal creature it uses its dex modifier on attack rolls instead of its strength modifier, because, like other incorporeal creatures (Spectres, Wraiths, etc), a manifested Ghost has no strength score (or cannot make use of it) when dealing with corporeal creatures.

What does this mean regarding feats that have a strength score as a prerequisite like power attack or cleave? Can a manifested Ghost still use them?

– And (by the way): is there any way (by feats ore magic items), a manifested Ghost can make use of its strength on attack and damage?

Background: I am currently preparing a little scenario with a knight who turned into a ghost long ago but still dutifully defends his castle. I do not want to him to moan, make touch attacks or gaze but rather fight like the old style chevalier he used to be (and still thinks, he is). I equipped him with a ghost touch weapon, so that his attacks vs corporeal creatures do not have a chance to fail. But, seemingly, becoming a Ghost has some disadvantages for someone who used to rely on strength a lot …