[*] Costs and risks for using the tadpole powers - Tadpole powers are just free power ups, without any noticeable negative side.
I can see value here. Although there are consequences, there should likely be more consequences in dialogue options, particularly at a certain point (and once a certain decision is made).
[*] Less XP in late game - You kill a random lv 1 vampire spawn who poses no threat? 400 xp, kill a bat with 1 hp? 210 xp. As an result, you quickly reach the lv cap.
I personally find that far too many combats late game seem to be designed around the level cap being achieved and find myself scrambling for XP just to overcome them. So, I would say that the XP amount is balanced (more or less) for somewhere in-between your skill level and mine? Either way, perhaps the solution is an additional skill level?
[*] More options to get rid of the parasyte. For eg, trying to bargain with Cazador to become a vampire. Or to the mage on the Sorcerous Sundries leader to create a artificial construct body and transport your soul there. Or a deal with the Devil. You can make a deal to Raphael for a item but not to get free from the tadpole.
um.... Astarian is a vampire and has the tadpoles. So, thinking that isn't a valid solution. Deal with the Devil? Didn't Wyll teach you anything? The construct is an interesting idea. But if that were an option, seems to me that a certain Arch Mage might have taken that way?
[*] More ways to kill Astarion
LOL
I don't have much to say about the rest.
I do have to comment that this post kinda makes me think of a post back in the day where the poster was commenting about how easy it was for them to beat Drzzts. Turns out that his blades couldn't damage Were-Bears. Who knew? But hey, play the game your way. Have fun with it however makes you happy, (you not necessarily pertaining to the original poster). I honestly hope everyone has fun with this game.