I used to sleep with my mother very often. my two sisters and i still cuddle our mom when we see her. i never once had that feeling sleeping with my mom. maybe your privates were being pushed against which could cause stimulation. i think you were too young to have any kind of sexual desire or knowledge my guess is it came from physical stimulation. little children often rub up against thing for genital stimulation but they have no sexual understanding so they do not associate it with sex. all they know like you said is that theres a good feeling.
normal. Besides the physical aspects of arousal due to skin stimulation a child is aroused by feelings of safety and security. there are also other ways to get aroused,people with certain hearing are aroused by sounds especially light sounds near the ear. Certain smells arouse other people. These are all uncontrolled by your body
I'm sure your arousal was physical and not mental. Very natural and nothing to worry about. Don't let small minded people confuse you.
By the way, if you read Freud you will understand there are stages where children get in love with their parents. It's part of normal development.
No that is not normal, please seek help asap.
Not sure if it is normal or not but cosleeping is in some places in the world and I wouldn't think about this. Most people as adults don't have super clear memories and who knows if you'd have had the sensations laying by yourself. So, stop worrying about it in my opinion. good luck