Is it ok policy-wise, if <!-- and //--> are removed from the ad code that Adsense gives us? The reason am asking this is only if those are removed are the ads appearing (when the code is pasted inside a .tpl file). Thanks in advance.
Of course you can delete this comment line from code. As you mentioned above in some scripts(like .tpl) you need to place code in one line. So it's necessary to remove comment line otherwise all code will be treated as comment.
It is better to ask this to adsense support itself. If you get something from then Post it here so that everyone can know it.
I have removed this line from my code to set adsense into my script. I haven't got any mail from google yet. I think you can remove it, though ask to adsense help center.
Personally, I think it's better to ask Google and get a real answer than just guess it's OK and risk problems with your account.
You are allowed to edit the code that is generated, as long as it doesn't change the format the ads appear in. You can edit the colors/image_text/size and anything you like. Peace,