How To Resize A Layer's Dimensions During A Script

Question #1:

I am not sure if this needs to happen every time the mockup script is run, or if you only need to set up the layers correctly beforehand.

If it only needs to happen once to the template before it is used to populate mockups, then just dupe the layer move it and then reset the clipped layers back as they were.

If this needs to happen each time the script is run, then you will need to automate the steps.

There might be a way to script this using the internal layers structures that mark the beginning and end of clipped layers, however, that is beyond my scripting abilities.

Although the following can be scripted or possibly put into an action, I will detail the manual steps:

1) Copy the base layer to the clipboard

2) The base layer of the clipping mask and the clipped layers need to be protected, encapsulated in either a group or as a smart  object.

3) Paste in place the copied base layer so that it is placed at the top of the layer stack.

Optionally, you can ungroup or convert the smart object back to a layer group and then ungroup if you wish to have the clipped ayers back as they were.

It's also possible to duplicate the base layer to a new document, then duplicate the layer back to the original document rather than copy/paste in place.

Question #2:

Smart object sizing uses the PPI resolution value of the smart object image vs. the parent containing document's PPI value. So start by comparing the PPI resolution values of the parent document and the edited smart object document. At the same time, compare the height in pixels of the parent containing document's layer compared to the edited smart object height in pixels.