Hey there, and welcome!
First, the beginning part of the game where you wander around hommlet is a bit misleading. They're easing you into the system, and it become much more combat heavy as you progress, though there is another town later that you also explore. Not sure if you will like the change or not. Most people find Hommlet somewhat boring, at least after the first time through. Lots of running around back and forth. You're right that it's pretty meditative, though.
Your problems:
The looting (and I think the door) problem is the infamous "looting bug" that is supposed to be fixed by temple.dll. That it is still a problem for you may indicate that temple.dll did not get successfully installed, which may be because you're using the Polish version. I could not say for sure. You should probably ask on the forum at
www.co8.org. There are guys there who know the code of the game very well - they're making a new game themselves! And they're very helpful, if their advice is sometimes technical and hard to follow.
The magic missile freeze could possibly be related to something in temple.dll. If that isn't installed correctly (remember, you have to do more than just put the new .dll file but also add the folders provided in the .zip into your game's data folder). Part of what was done to fix the looting bug causes problems with the magic missile spell, and that's why they also include new code for the spell to be put into the data folder. Often, but not always, magic missile will show that you have -511 missiles to fire, and when you try to shoot them off the game freezes. Sometimes it seems normal but the game freezes.
In short, it's possible your fix is as simple as adding to the data folder. If you did, it may be a language/version issue, and you should consult co8.
Hope that helps.