How to initialize plugin UI with data from document on initial render in Figma?

To add a new stroke on rectangle in Figma do as follows:

• Select Stroke option which will give you the option to adjust the stroke size and color.
• You could alter the angle of the stroke as well.
• Add shadow to give it a smooth finish.
• You could also choose which side you want to bend your stroke style.
• Choose the stroke bent inside.

• To rename a layer in Figma right click the layer you want to rename > Choose ‘Rename’ > Done.
• Directly press Ctrl + R then write the name of your choice.

You could add local paintStyles to node by using:
Shape.fillStyleId = localStyle.id.
Note: Shape being any shape of your choice in ‘Shape.fillStyleId’

Yes, but only when you are using the published version of plugin and then use it.

You can make a component instance in Figma:

• Open the Assets panel.
• From the left sidebar select Assets tab.
• Find the component of your choice.
• Click and drag the component onto your canvas.