I am looking for clarification on how some spells fixed to a hallowed site actually work in this manner.
Darkness is easy. The entire area is one light level lower.
Bless and bane seem a bit trickier. Does everyone who enters the hallowed area that is fixed with a bless spell receive the bless bonuses? Or is it just allies? And if so, then that means the bane spell only affects enemies, so...does the bane spell have no effect on creatures that are neither friend nor foe?
Protection from energy makes no distinction between friend or so, so does it affect everyone who enters the area? And can a creature "renew" the casting by simply stepping out of the area and then back into it? Because it seems like this would essentially provide an immunity to energy as long as the creature can keep stepping back and forth before the damage limit runs out on the first casting.
Detect evil...is the area treated as if the caster is concentrating each round? So, if an evil creature steps into the area, the caster senses this automatically? Or at least on his turn? And just the caster need to be in the area too? Or does the caster have to be in the area and use a standard action to concentrate in order to sense the evil?
"You may designate whether the effect applies to all creatures, creatures who share your faith or alignment, or creatures who adhere to another faith or alignment."
Bless and bane seem pretty clear in this sense. Whichever clause you pick (all, only same religion/alignment, only different religion/alignment) determines who are allies or enemies for these spells.
Same with Protection from Energy, it effects everyone you set it to effect. As far as refreshing the effect, it seems to be in place as long a creature is within range and immediately ends when they cross the threshold (same as the other effects). The issue I see is that no caster level is set for the spells fixed to a hallowed site. I assume it uses the CL of the cleric/druid who cast hallow in the first place. So, yes, it seems that you would get effectively complete immunity to a single element as long as you run back and forth across the edge of the hallow range. Just hope you don't get Dragged, Bullrushed or Repositioned.
Your guess is as good as mine on how Detect Evil is supposed to work...