Opening theory

As a novice just starting out on chess (chess.com ELO 1100 - 1200), I am unsure whether I should learn opening theory (this is important - by "learn", I mean that I will study and actually understand why the book lines are the best). I will attempt to explain my predicament below:

When I play with other beginners using the Live Chess feature, I meet two groups of people: 1. the ones who don't know opening theory (it's quite obvious from their opening moves)  and 2. the ones who do. When I meet people from 1., a 'good' game will result and I have a fair chance of winning (or losing).

However, things become quite different when I play with people from 2. Some of my opponents know the openings I play rather well and I have a positional disadvantage later on in the game because of not-so-good opening play on my part. Pyschology also plays a part in my game - I am sometimes rather afraid of playing a 'bad' move which may result in a strategical disadvantage, especially in openings I am unfamiliar with.

A few things you should take note of before attempting to answer my questions below:
1. I am aware of the basic opening principles, which I attempt to fully utilise in all of my games.
2. As white, I prefer to play 1. e4, and my opponents frequently respond with 1 ... e5.
3. As black, I will respond with 1. ... e5 if my opponent plays 1. e4, or 1... Nf6 if my opponent plays 1. d4
4. I am a beginner.

So, the crux of the matter:
1. Are my fears justified? Will a strategical disadvantage result for me (at the level I am playing) if I don't playing an opening well?
2. Should I learn (study and understand book lines) a FEW openings which are useful for my game?
3. If the answer is "yes" to 2., which openings should I learn, based on the information I gave above?

I am hoping that intermediate and advanced players (ELO > 1500) with a fair amount of experience can answer my questions.

Well, you should always try figure out after the game what went wrong, and how you could have played better. That counts for the opening, middlegame and endgame.

But it's useless to play moves that you don't understand -- you won't know what to do in a slightly different position, and when your memorized moves run out you don't know what to do again.

You might end up at a strategical disadvantage if the opponent plays the opening better than you do, but the same holds for any other phase of the game, and it's usually a lot more lethal if it happens in the middlegame.

Get some basic strategy working for you first, that increases the number of openings that you can play and is generally good for you.

If players of your rating are superior to you in opening theory, chances are good their play lacks in the later stages. Keep that in mind and don't resign too early.

Either way, try to remind yourself that losing to an opening trick is actually a win for you, especially if it turns out the trick has a counter that would leave you with the advantage. After all, if you got schooled, someone provided the schooling and didn't receive any themselves - rather a one-sided deal! Sometimes you can figure out the counter over the board, but if you can't, figure it out later, or post the games on the Opening Theory or Game Analysis forums in here. You can disregard losses where you simply dropped a piece like a beginner (you are), but if you don't know where you went wrong, you owe it to yourself to find out.

Make sure not to overestimate your opponent's play. 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 looks like it just picks up a pawn by force and possibly loses you an exchange too, but Black is very much fine. That's an example for a book line that can be worth having a look at as a beginner!

There are 1300s, 1400s rated players who play crap openings (sometimes, it seems, on purpose). They will still likely beat you since they are that much better at tactics. Kind of like Sleeping Beauty; eventually they start playing chess. So, play, play, play! Do tactics puzzles maybe, then play some more. Make mistakes, then learn from them.

It might help if you post some of your games that are examples of you being outplayed in the opening by an equally-rated opponent - we might be able to shed some light.

Good points Silfir.