No, it wasn't. Oda had made it clear that Luffy's mother was not part of One Piece and that the character would not appear. Furthermore, if Sir Eam was Luffy's mother, it would be very illogical. This was because Luffy was one of the people Sir Eam had 'killed' back then. It was impossible for a scene where a mother killed her son to happen.
There could be an original character created just for the fanfiction. A woman with a kind heart but a tough exterior, who was a great fighter. She could have met Luffy's father during a battle and they fell in love, and she became Luffy's mother.
In One Piece, Luffy's mother was not explicitly mentioned. Oda had once said that mothers were the natural enemy of adventure. Luffy began his adventure after leaving his mother's embrace, so Luffy's mother was not part of the story he told and would not appear. However, there were many speculations among the fans. For example, some people guessed that it was Seven Martial Haisha Krokdal. The reason was that Old Sha looked like a girl in a photo when she was young. Ivankov could change people's gender and said that Old Sha had something on him. They speculated that Old Sha used to be a princess of a fallen country. After being saved by the dragon, she fell in love and gave birth to Luffy. Later, Ivankov turned her into a man. There were also people who guessed that it was Sir Eam, because Sir Eam was holding Luffy's bounty and had the same huge straw hat as Luffy in front of him. However, after Luffy's voice actor, Makoto Tanaka, asked Oda for confirmation, this speculation was denied. There were also people who guessed that it was Luffy's hometown, the owner of the Windmill Village bar, Makino. However, Oda's drawing of Makino holding a child overturned this speculation. There were also people who thought that it was the red-haired sisters, but there was no conclusive evidence.
She could be a former pirate captain herself. Maybe she was one of the most feared pirates in her time, and her skills and reputation were passed down to Luffy in some way, even if he didn't know it was from his mother.
One idea could be that Luffy's mother was a powerful pirate herself. Maybe she was part of a crew that had a special mission, and she had to give up Luffy to protect him from the enemies she made at sea.
Sir Eam wasn't Luffy's mother. Oda once said that his mother was not part of One Piece's story and would not appear. Luffy's mother did not belong to this story. From the logic of the story, if Sir Eam was Luffy's mother, it didn't make sense for him to kill Luffy. Moreover, judging from Eam's gaze in the animation, the possibility of Eam being a man was extremely high. So, Sir Eam wasn't Luffy's mother.
There could be. Fanfiction is a place where all kinds of wild and creative ideas come to life. The idea of fem Harry being Luffy's mother is quite unique and would attract a lot of readers who are into crossovers. Some fanfic writers love to blend different universes together, and this would be a really interesting blend. But finding it might take some time. You should look for fanfics that deal with character relationships in an unconventional way and also check for any tags related to gender - bended characters from the Harry Potter series in the context of One Piece.
As of now, the true identity of Luffy's mother had not been clearly revealed in the original work of One Piece. Although there were many speculations, such as some people believed that Luffy's mother was a Heavenly Dragon, and speculated that the dragon and the female Heavenly Dragon loved each other and gave birth to Luffy, but were forced to separate due to the rules of the Heavenly Dragon, which led to the dragon's hatred of the rule of the Heavenly Dragon and the establishment of the Revolutionary Army. There were also speculations that his mother was a Sandia, and the reason was that the tattoo on the dragon's face might be related to the tattooing custom of the Sandia. There were also some strange speculations, such as that she was Shanks's sister, but these were just fans 'speculations and not the truth officially announced.
In One Piece, Luffy's mother didn't have a clear official setting. There were many speculations by fans. One was that Ace was the posthumous son of One Piece King Gor D. Roger. Ace and Luffy were half-brothers. Luffy was also Roger's son. Luffy's mother was Monchi D. Dragon, but this theory lacked official evidence. There was also a theory that Luffy's mother was a Heavenly Dragon and was imprisoned in the Heavenly Dragon prison because she secretly descended to the lower realm and gave birth to Luffy with Monchi D. Dragon. There was also a saying that Luffy's mother was the sister of the former pirate king, Gale D. Roger, and that Luffy's grandmother and sister were " fabricated." There was also speculation that Luffy's mother might be a pirate, but these were not confirmed by the authorities. According to Oda's answer on SSS, if his mother appeared, she would interfere with Luffy's adventure, so he simply didn't let this character appear to ensure Luffy's normal adventure.
In cartoons, 'put em up put em up' often means to get into a position of defense or to display something quickly. It's a common phrase used to create tension or prompt action from the characters.
I'm not really sure. It seems like a pretty random and confusing phrase. Maybe it's related to a specific comic or a unique catchphrase, but without more context, it's hard to tell.