Correct - keys are very important.
And another thing: In Div you were used to getting a skill book and having access to the skill at once. This is different in BD => you buy a skill, get a book and it only OPENS a skill (path). In order to activate/use a skill, you need to have skill pts of your own and put them into the skill.
Combat is slower, because you have restrictions, due to your stats. So, you don't need to click very fast.
If you wish to look at all skills you can get in the game => look at your skill table and click on the small table => you will see all, even if they are not opened yet.
Kiya
http://www.kiya1.de/demoscreens/democom10.jpgI don't know if this link will help you to get accustomed to fighting, as I made it for mages - but maybe some descriptions will help. Sorry, for the small writing.