i think it's interesting that your rating is in the 1800s and you don't know a good opening for yourself. i also think it's strange that you claim your rating is 1800 but you don't know where to look for openings and ideas behind openings. it's probably just me though.
In dire need of a pet line...

Hello to you.
It seems that you don't like theoretical openings, so as white I suggest 1.d4 where you can get into positions such as the Grunfeld or King's Indian where it's more tactical and positional rather than theory and memorization. I know you said that you are more tactically sound rather than positional and you do often get the Slav defense 1...d5 in return to 1.d4 and then it becomes a little more positional, depending on the variation. After 1.d4, the common reply to black's move is 2.c4 where you control the center. You could also try and play into the Catalan, but I have never played that myself so I hope somebody else can give you information on that.
Against 1.e4 I usually respond 1...c5 and enter the Sicilian or 1...c6 for the Karo-Kann. I hate playing into the Ruy Lopez so I avoid 1...e5 in response to 1.e4. The Karo-Kann is more postition than tactical in my experience and I have had to play in very cramped positions.
As for in response to 1.d4, I usually play 1...f5 getting into the Dutch. And after 2.c4, I play 2...e6 getting into the Dutch Stonewall variation. This is more tactical than any other line in my opinion and I have had quite a number of successes with it against some of the top players in secondary schools here.
In response to the Sicilian, I recommend for you the Closed Variation which is 2.Nc3 rather than the more common 2.Nf3. This does set itself up for more a positional play. You said you aren't aggressive nor defensive, so in other words, passive, you can always try after 1.e4 c5 2.c3 which is the Delayed Alapin, and your aim is to go for a future d4 push in the short term. This does lead into tactical territory where you need to co-ordinate mainly your knights together.
I hope it helps. Don't be deterred by the fact that my rating on chess.com is so low, I am much stronger OTB than online. I tend to see and focus more in OTB games.

Your whole post is much too broad, really. It comes down to "what's the best opening?", and there isn't one.
So I'm giving just some general tips:
1. Stick with what you know. You have a number of openings you already know somewhat, but you can probably deepen your knowledge of them a lot still. Of course it's fine to change openings, but change one of them per year, not all of them at the same time, that'll lead nowhere (you won't really know any of them, and you'll keep switching around). Find out with which opening you get the worst results, and find an alternative for that.
2. You have no style. You have a bunch of weaknesses. Grandmasters have a style. For instance, you say you both have a "universal style" and are more tactical than positional (whatever that is). What you probably mean is that your middlegame strategy needs work. So work on that. (Actually, I now notice that that's more or less what you're saying. But this is general advice ;-))
3. There are no openings that good, and aggressive, and light on theory. All the top players play good openings, so that is where the theory is. Fact of life. Luckily, you don't really need to know much of it at lower levels, except for the two or three razor sharp tactical positions that you can't really avoid in an entire repertoire, and then you just collect the lines and memorize them. Life will go on.
4. To learn a new opening, play it. Then afterwards, go through it, see what went wrong, what you should have done, and why. Repeat. Also play through annotated games in your openings. Also, what I do is to go find a repertoire book on the opening on Amazon (e.g., Play the Caro-Kann, etc), look inside the book for the variation index, then start playing those variations. That way you have a mini repertoire that is already quite useful at low level, and if you like the games you get you can buy the book.
For explanation of general ideas, one place to start is Wikipedia, but of course that's extremely limited (it's usually more a list of variations). Watson has just written a 3-book series about ideas behind the chess openings, that is probably a great place to start.
Hello. My rating is currently somewhere between 1800-1900 and I REALLY need a good solid opening repertoire. I stopped playing for about two or three years but then I've gain interest in the past year or so. I always used to play e4 with Ruy Lopez as white and e5 with whatever comes as black. I'm sick of doing that opening though.
First off, I think my opening style would be classified as universal because I have no preferred circumstance of position. I can defend if I need to, attack when I need to, etc. However, I do think I am way more tactical than positional and I need an opening that is tactical.
About a month ago, I decided that I might do Ruy Lopez as white and Najdorf Sicilian as black. But then everybody's been telling me: Oh. Those openings have so much theory behind them. You'll need to memorize tons and tons of lines behind them.
I do not want to memorize endless variations. I mean, if it's completely necessary, I will, but I'd rather learn some main lines, play it by ear, and learn the general ideas behind them.
So what recommendations would you recommend? Sorry if I'm being really vague with my descriptions of my own playing style, but that is because I don't even know it. I'm not aggressive or defensive. I don't prefer one type of position to another. But at the same time, I'm more tactically sound than positionally sound. I would like:
1. an opening as white
2. an opening as black against 1. e4 and 1. d4
3. an opening against the Sicilian
Sorry if I sound really picky, but I cannot seem to figure it out for myself. Any suggestions? Thanks so much.
P.S. Where can you find information about the general ideas behind each opening? Thanks.