This is a long shot, but I wonder if this is The Amazons of Somelon by Raymond Kaminski.
This kind of matches your description, but only if you've misremembered some elements of the book. The Amazon lady is Sheryl and the queen is Allukah, though Allukah is not a troll - she is the queen of a barbarian horde called the Horlas.
The Amazon Sheryl does indeed get a bash on the head. She is knocked unconscious when barbarians called Horlas attack the caravan she is guarding. But I can't find any reference to a talking Sun and Sheryl doesn't turn into a troll.
The chap who is castrated is Kio though he isn't exactly castrated just, erm, left rather mauled by Allukah's attentions:
As Kio shuffled along, the aching orbs between his legs slapped from one thigh to the next, swinging like pendulums. The entire foreskin was gone from his penis, shredded by Allukah's coarse hair, coarsened by her two sets of chapped lips, and gnawed by her crooked teeth.
The part with the dead father's corpse is when Kio finds the mummy of Allukah's father, though the penis isn't used for any rituals:
Kio found her father's body in a small room lined with stalls and white porcelain bowls, exactly where Allukah had hidden it. Lugging the stiff corpse ripe with embalming fluid all the way out to the light, he scooped a hole in a soft heap of rubble with his bare hands and placed the dead man inside. Kio was particularly careful to bring the mummy's severed penis along too. He knew what it felt like to be half a man, even if he didn't know what it felt like to be dead.