As with raising a girl, I'll teach him kindness and all the things you teach ALL children, but there a underlining responsibility in raising someone outside your accepted gender. I don't know how to be a boy. I don't know what it feel like to have a penis and use it. I don't what it is like to be a male and make decisions as male.
22-year-old straight cis dude here with a great father (who is still married to my mom). Other than playing catch in the backyard and some sports, I can think of nothing that my dad did that my mom wasn't equally capable of doing (and tons of great athletes don't have a father in their lives, i.e. Lebron James). Sure, my dad taught me how to shave, but anyone can teach a child how to shave. It wouldn't have been weird at all if my mom taught me. Sure, my dad did a sex talk, but my mom did a separate sex talk that was a hundred times better.
As for giving advice about using his penis, if either of my parents ever sat me down and gave me instructions on how to use my penis, I would cringe and run out of my room. That's the case whether I would be 8, 12 or 22. Unlike vaginas, penises are incredibly low maintenance. If he's uncircumcised, make sure that he knows how to wash under the foreskin. (I'm circumcised, so I don't really know how). Look it up online or discuss with the pediatrician, because I'm not 100% sure if this is what needs to be done. When he gets older, make sure that he knows how to check his testicles for cancer and lumps, and make sure he knows how to detect STDs and how to put on a condom. This is all stuff that should be covered in a typical sex ed lecture and if you aren't sure if you should discuss this stuff with your child, just ask your pediatrician. Your pediatrician could probably also discuss this with him. He'll figure out masturbation on his own, and otherwise, there's nothing that you need to discuss with him about his penis. No periods, birth control or any of that other stuff that you'd need to worry about with a girl.
Here's an askreddit from a lesbian couple pregnant with a boy. Read through it. It can probably help soothe most of your anxieties about raising him. http://www.reddit.com/r/AskReddit/comments/1qlh8f/two_women_raising_a_son_what_might_we_not_know/
I can't help you with your dating problems, or with how your son may react to a new boyfriend. But there are tons of resources out there that can help you. I'm sure that there's a subreddit for single parents, and I'm sure that there are dozens of books and thousands of articles if you search on google or amazon. If you're still not sure, find a therapist who specializes in working with parents, and ideally with single parents. I'm also sure that you have friends raising a son, so don't be afraid to reach out to them with a question.
Just be the best parent you can be and I know that you'll raise a great son.