Hey there, Vividreamer!

Wow, great that you can dream lucid that easily! I admire that!

About the sex drive: this is normal and very common. Dreams are in fact products of your subconscience, and no matter how 'civilized' or decent you are in reality, in dreams your subconscience dominates. And the subconscience is all about food, violence and sex. When we are awake we can constrain ourself and when we feel like wanting sex, we do not just jump at somebody and do our thing. But in dreams there is no constraint. Freud had some great theories about that... So this is normal and not 'wrong' in any way.

Dream control is all about confidence. I only had 2 lucids, but in both I was able to control my entire environment. For me getting lucid is the problem! But anyways, you have to be confident and believe in yourself while you dream. Don't just command your environment, but expect the environment to react the way you want to. You have to believe in it. Constantly keep in mind that you are the master of your own dream, you are inside your own head and you decide what happens. Thats what Blairbros means with dominant ego, I think.
Little tricks might help. If you find it too hard to just summon a rainbow out of nowhere, do it VIA something. Like... open the watertap and expect a rainbow to come out. If you find it too hard to teleport, turn your closet into a magical teleport machine and do it VIA that machine. Thing is to keep it "realistic" for your brain, which is easily done when you use all these little tricks.

Of course I'm just a newbie, but I hope my knowledge was of some kind of use to you. ^^ Good luck with your next lucids!