The conversion to jpg or any non-Geo format will strip the location info, but will not change the number of pixels in height or width. The world file I mentioned is a text file with a few lines of info that tell most CAD and GIS progs where the image goes, though you do have to know the coordinate system the image is on.
The real interesting thing to your question is if the program using the tif actually re-projects the image, or just uses corner info to place it. GIS progs will reproject, and that will be very slow for these large images from drone flights. The first thing I do if I care about that, is use QGIS to save the reprojected image to my project (CAD) coordinate system. Then I can make the world file and not need any reprojecting in CAD.
In Google earth, the kml just has image corners, and converting to jpg will not change that as GE does not reproject.
Its true the learning curves involved are harsh, and you need a set of tools for testing things. Luckily, I do both CAD and GIS and write add-on software for both so feel free to keep asking anything. I specialize in avoiding pay software but also not compromising on tool quality and the free and low cost options out there theses days are candy waiting to be eaten.