customs exemption

Hi, I read this in a newspaper: customs exemption. Why is customs not in singular like ‘‘shoe shop’’, ‘‘sport centre’’ etc. ? And one more thing: "If you can show me the way, I (will/would?) be grateful.’’ thanks.

Customs in plural has a special meaning that the singular usually has not, that of the procedure you go through when you enter another country. In addition, the singular can be both (substantive) noun and adjective, as in a custom-made dress. The plural is the only option here that is not ambiguous.

Will is better, though I believe some native speakers might also say would - would is strictly speaking a hypothetical situation.