For Proofgrade, you can populate the settings for the material in question by selecting the material (or auto-detecting the material). It will apply the cut settings automatically to an object that’s designed with a stroke and no-fill.
If non-Proofgrade, it’s going to depend on the material and you’ll have to test to see what works best. You can search around the forum for various material settings, or start with Proofgrade (if we talk too much about settings, we’ll prolly need to bump this over to #beyond-the-manual).
You can do that. As @chris1 mentioned, you’ll have to visually align to center - the UI doesn’t have a snap to center or anything like that.
Using Illustrator verbiage, you can place your raster artwork (image) into the Illustrator file. When you go to save the SVG, just make sure the option to embed is selected. That way you can have your vectors and rasters all in one file and placed exactly how you want corresponding to one another.