The Chronicles of Spellborn

If you mean a health bar view , yes but the target hast to be actively selected. If you are running your mouse in fps mode, it's difficult to select the target but possible .

almost, i meant 'target of target'
Edit: maybe this picture is a little clearer http://i.imgur.com/eGPsOwp.jpg (the upper one)

Nope, wasn't possible so far.

Watch this video, it is self-explanatory:
 

Are there any skills that display a castBar?

I'm not realy sure about that, mostly played my warrior.
For some spells there were circles drawn on the floor, for example for poison attack, or healing.
Maybe Acid knows a bit more on this, he played more the caster type of characters.

By cast bar do you mean where the skill should land? If so yes.

like this:

(bottom center, displaying the name and percentage of the spell as Casttime until the spelleffect is executed)

Back then, was it possible to unequip weapons? or were you only able to 'change/swap' the weapons?
When i chose a skill without having equipped the correct weapon, the character reverts to the T-Pose, so it looks like you couldn't do that, no?

There was no option via skill bars to swap weapons but you had to open the inventory and the equipement screens. You could equip single items by just double clicking (or menu selecting "equipe") in the inventory. Rings were easier to place by sliding them from one window to the other.