4) There is no tutorial or perhaps a small tooltip at the start of the game. But overall you drag and drop an item over another item in your inventory and it will create a new item - a popup window appear to ask you to confirm the crafting. Ex:
Drag any dagger over a pillow or Drag an empty potion flask over a Penny Mushroom (not sure of the name here...) You can always google, but right now not much information is available.
5) The level up system is indeed very confusing as to how many stats point you get each level. I am not sure it is showed in any tooltip (which would be appreciated btw). I found a Dutch website that had all those stats available but right now I don't find it...
But I know that you get one skill point for the first 5 levels. Then 2 for lvl 6 to 13 and then 3 from lvl 14 to 20 (I am not 100% sure of the lvl#). Talents you get one... each 4 or 5 level? I think.