Your thoughts and experiences are quite common and very normal. Many of us here, including me, have related similar - happily married or partnered but there is that extra thrill you get from being with a man that you don't get from your partner. You love her, and you love sex with her, but she doesn't have a dick. Welcome to the club.
1) Is it okay to just love the act and the result, and not be "attracted" to the guy, per se?
Yes, absolutely. Sex can be simply a physical act for physical enjoyment without the need for attraction and connection to the person. This is quite common and normal for many of us here, and I'm exactly the same: I love dick but I'm not attracted to men in the same way as I am to women. I think this would only be wrong if the other guy was looking for attraction and connection, and you deceive him to get sex just for the act. so long as both people involved in the act understand that it's just for physical fun, then it's absolutely okay, IMO.
2) I find that once I cum, I am done with the encounter, so in many ways, it is better that my partner cums first and then I cum.
This is so normal that it has a name: post-nut clarity. You're super horny and overcome with the thrill of the action, and then once you cum, it's all over and you're done with him and his dick - you can't get away from him fast enough. As you say, the appropriate solution is to ensure that he cums first. It's a common and normal thing when you're having sex for the physical thrill and not attracted to the guy per se. Never feel like there's anything wrong with this. It's only wrong if you let down the other guy.
3) I get absolutely over the top with excitement when getting together with a nice looking partner. It gets to the point that, if we are making out, sucking each other and also rimming, that I just want my partner to enter me and have his way. Penetrate me and cum inside me.
I feel exactly the same and I believe many bisexual / straight-leaning / bicurious guys feel the same - there's a special thrill in submitting and giving yourself to a man. I think it stems partly from the role we take, and are often expected to take in hetero sex, where we take the lead and guide the action. It's nice to be the one being led and to take a feminine role. I find I feel a sense of bonding with the guy and a special pleasure in feeling him using my body for his enjoyment.
So, am I considered a true "bisexual" man if I love the act, but not necessarily needing to love the man? I have come to realize that I cannot ignore the fact I am bisexual, and that I want to experience this with another nice, clean man. I have a lot more to comment on as well.
I'm not sure what a "true bisexual" is, as opposed to a not so true one. I think there's a spectrum of bisexuality and it's fluid in many of us between straight-leaning and gay-leaning. If you mean, are you bisexual if you love only the dick and not the man? Sure, why not? That's how I consider myself to be. The important thing is to feel comfortable with who you are and what you do, and don't stress too much about labels. Labels are for fruit in the supermarket. You don't need a label to understand yourself and be comfortable in your own skin.
I hope it helps you to feel better about yourself knowing that there are others like you who understand. If you want to know anything more, feel free to ask.