Place an `@` in front to the `ini_set()` statement. That will supress the warning. The one in functions=filter.php is more of a problem. It is required for the filtering to work correctly.
Unfortunately some providers think that they are being helpful by making these "security" restrictions. Not much you can do about that but speak with your service providers an point out that the uses made by Zenphoto are perfectly legitimate.
Either that or find a provider who is not so draconian.
Edit: you can disable the plugins whose names begin with `filter` and maybe not get the `debug_backtrace()` warning. Of course, then the features they provide will not be available.