I haven't read all the posts yet, just the first one I'm afraid.
I thought that, since I identify as Pansexual myself, I should perhaps put my own two cents in.
I just know that I could fall in love with someone regardless of their gender, age or pretty much any other physical trait. And for me, love is necessary for sexual attraction. I'm sure that it doesn't work the same way for everyone, but I think that the way that I'm wired (mentally) in other aspects lends itself to my sexuality.
For instance, I'm the kind of person that just.. isn't ... turned on by porn. I can't look at sexual images or video of random people and become sexually aroused by it. Actually, for a good portion of my life, I actually thought there was something "wrong" with me because of that.
* It's different, though, when I'm looking at the naked body of someone I've come to care for or naughty photos/video of myself with others.
Likewise, I've never been one to enjoy a one-night-stand or anything of the like. Though, I have tried them out before. I'm also very monogamous.
It might sound odd, but I'm not attracted to a lot of sexualized body parts. Whatever's between the legs, butts or breasts just don't do it for me on their own. There are body parts that I do find attractive, though. These are eyes and hair... I will go so far to admitting I have an actual hair fetish. I like long hair and big, emotive eyes, regardless of gender. I also tend to like androgyny, particularly with men. A very macho man is a turn off for me, but personality could make him attractive.
Another thing that I've been told is strange is that I only have eyes for the person I'm with. I love my significant others with a singular devotion. I don't look at others in a sexual way when I'm in a relationship. It's as if my ability to find others as sexually attractive just turns off. When I'm single, that isn't the case though.
And, when I'm with someone, it's as if they become the most beautiful thing in the world to me. Suddenly their genitalia is something that turns me on, as well as the rest of them for that matter. I've even come to love the hairy belly of my husband, something I had never had any desire for in the past.
I don't think that the way I am is any better or worse than the norm. It takes all kinds to make the world run. However, it does make me sad when I'm with a very straight man and he says if he woke up one day and I suddenly had a penis, he wouldn't want to be with me any more. That makes me feel like the love he has for me might not be on the same level of what I have for him because I would still love him if he were suddenly female. But, I'll admit that it's hard to wrap my head around another person's sexuality some times.
I hope that I made enough sense for everyone to understand me, as different as we might be. ^.^'