I love fantasty fiction and love the whole premist behind D&D although never really playing it and therefore not totally understandig all the gameplay and mechanics. But I am very interested in this game and was wondering of two is good or does it have to mnay bugs and I should try 1 first?

It depends what do you expect. These are two quite different games. In NWN1 you have full control only over your main character. NWN2 is team based and you can give direct orders to all your characters (it's closer to Infinity Engine games - Baldur's Gate, Icewind Dale, Planescape Torment). D&D rules implementation in both games is quite similar. As for bugs, there are chances you'll experience a few in NWN2, but they aren't game breaking. NWN1 EE also has some single bugs left. For an overview of single player campaigns from both games check posts in this topic: https://www.gog.com/forum/neverwinter_nights_series/nwn_1_2_single_player_campaigns/post3. If you haven't played any of the NWN games, I suggest you start with NWN1 EE. Unless you strongly prefer team RPG's that is.

If you're after a single player experience, skip 1 and go to 2.

The campaign in 1 is really terrible. Actually, at first the developer wanted to make this game multiplayer only. The idea was to recreate the experience of an old-school tabletop session with DM and your friends. But ultimately they decided to put in a single player campaign. The end result... was not pretty.
I bought it as soon as it released (in Poland, so about a year after its original release). And, oh boy, was I in for a dissapointment. It made me stay away from NWN expansions and sequels for years.

The expansions are better, but still not great (HotU is fine, but only the last act truly stands out). So you could skip OC and play both expansions (SotU starts you with a new character, and you can use them to continue adventuring in HotU).

NWN2, on the other hand, is much better for single player. The OC is a really cool high fantasy story with multiple agencies with their own goals. And actually one of my favorite evil companions in a cRPG. However, there are some slower, less interesting parts in it. Still, it's so much better than NWN1, I've always wondered why it kept the name. I would've picked up the game sooner, had it not been named NWN.
But, the expansion. OMG, Mask of the Betrayer. The Best cRPG Story EVER. And it actually lets you be truly evil, not just "hahaha, give me moar money!". Truly fantastic soundtrack is just icing on the cake.
I never could get into the second expansion. Usually, I just forget it exists. Some nice ideas, but ultimately the engine was not well suited for this kind of campaign.

However, if you've never played these kind of games before - be aware that character creation uses a very complex system (that's D&D 3.5 for you). And the amount of classes, skills, and feats you can choose from is simply staggering. That's actually a good thing, but may be off-putting to some people.

There aren't many references to NWN1 in NWN2. One of the merchans used to be a companion in NWN1 expansions. And there are some references to "the war" and "the plague". Fortunately, not many - for me, the less reminders about the trainwreck that was NWN1, the better.

Both games are great, but NWN2 is more polished and has a better story. The potential party members have more depth and interactions are a lot more interesting in NWN2. There are a ton of faqs out there that talk about the game mechanics and character builds for both games. There is also the neverwinter vault, where you can load fan made mods. There are hundreds of mods and many are really well done.

Considering the official campaigns you may be right, but let's not forget that both NWN games explicitly came with the tools to create your own adventures and both games are heavily about the modding communities as well. In that regard, NWN has tons of high quality single player content, much more so than NWN 2.

To the OP:
Even though I like that NWN 2 gives you control over a full party, personally I prefer the engine of the first game, and although a bit more dated and less colorful, I also prefer its graphical style and consistency. In NWN2 I often had issues with performance (it's very demanding for what it is, even on powerful rigs) and with the camera (often too close, clunky to handle), and the pathfinding wasn't that great either. Although to be fair, the first NWN has its share of issues, too, and neither are to an extent that they make the games unplayable. In the end it's just a matter of preference. Some prefer NWN, others prefer NWN2, many like either. Eventually you should get both games, they're both worth it.

Concerning the official stories, NWN2's main campaign makes some slight references at NWN's campaigns (you meet at least two characters from NWN in NWN2, but the stories are independent of each other and NWN2 is designed so that you can also enjoy it without knowing NWN.

Oh, and NWN2 has a lot more feats and abilities, so if you're easily overwhelmed by a lot of info and choices, character creation in NWN is a little bit simpler and easier to get into for someone not that familiar with D&D yet.

And this is mostly because the game engine doesn't support multi core processors. Game puts too heavy load for single core units to handle. It came out not a long before multi-core processors became a new standard. What's interesting Aurora Toolset utilizes two cores, if they're available. Too bad Obsidian didn't implement this feature in the main game engine. Performance would be much better.