RE: Sense gate metal1 in pcell(lowest hierarchy) and draw metal1 path to connect all gates in a row of 10 pcells in current hierarchy(1 hierarchy above than the lowest hierarchy).

In addition to what Tom said you might try looking at the rod* SKILL functions - each instance has a rod ID and you may be able to query shapes (like pins) inside of the PCell. By the way, if you couldn't descend or see into the PCell you wouldn't be able to use it, so I assume you are talking about edit access. But you don't need edit access to be able to 'see' the shapes inside the PCell. Using ROD would make things much easier because then you can use a function like rodCreatePath() to create a path from one handle (a point on the pin shape you identified from one instance) to another handle (ditto). Hopefully this additional hint may help you. Best regards, Lawrence.