Plamen,

Looks like format function is not supported in VBScript. Could it be?

>1. You can use "+" for strings - I think there's no differences between "+" and "&" for strings. But code with "&" is more readable - when you saw it, you know that this expression returns string.
>2. I never see official documentation how effective is some VB/VBScript function. So you can do your own tests with many CStr's and, for example, Str$'s and see what is the difference.
>3. About Trim() - I prefer safety to speed. If you hard test some function (IN ALL POSSIBLE SITUATIONS) and it never insert spaces, omit Trim(). But often I have no time to these tests...