You can find all the informations you need on the wiki.
Basically at the start of the game you're given a treshold of 30 Naughtyness.
Every action damaging a "nice" creature subtracts points from this treshold according to the following table:
When you reach 0, one or more Krampii (Krampuses?) will spawn, depending on the days you've survived:
Every 60 seconds spent not doing naughty actions will increase your threshold by one, so this means that if you try to space out your killings in time, you can safely keep hunting for your meat without fearing to meet Krampus. On the table above the "Treshold" column indicates the maximum naughtiness you can have. It has been put in there because it's supposed to go down the more days you play, but there's still an uncertainty on the exact numbers, hence the interval.
No.
It has nothing to do with serial keys, though. Even if GOG is DRM free, they often supply a serial key with their games. This is for your convenience. Should GOG one day go bust, you still have your serial key – which is your unique code, or "proof of purchase", if you will.
This should not be confused with DRM, though. DRM simply put limitations on how the game can be copied or transferred. A game with no DRM can still ask you to enter a serial key for a number of reasons.
A serial key should not be confused with a Steam activation key either. It's a separate concept. If you buy the game from a retailer, or from the developer directly, they will often let you activate it on Steam, so that it is connected to your account.
Some times, they may also give you a gift code for that specific game on GOG or other game platforms.
What you will not see, however, is Steam providing GOG codes or vice versa. The reason for this, is because they are competitors. It would be similar to buying a gift certificate at the Adidas store, which you can use at the Nike store – or Google Play versus the Apple Appstore. They would be a) cutting away the profit from their competitor and b) leading customers to the competition.
HOWEVER!
In some cases, Steam accepts the regular serial key as the activation key, but that does not include Don't Starve. You can see the list of games which accept third party keys here: https://support.steampowered.com/kb_article.php?ref=7480-WUSF-3601
Best Answer
No, it is not intended
I just started Don't Starve to double check: I can move around with WASD and meanwhile use my mouse to browse through the inventory. During crafting, you have to stand still (moving cancels the crafting).