As you're dealing with digital print output, Scribus may be a good option. That's layout (something of a mix of Illustrator and InDesign), not image editing, but cropping photos is easily done in a variety of FOSS without having to be subjected to the learning curve of GIMP (so long as your RIP can translate RGB into CMYK, which was a solved problem in the aughts). I've admittedly only played around with Scribus a bit, but from what I can tell from your use cases, you're not looking for the bells and whistles like trapping one needs for offset.
Ive tried Scribus, and found the interface very hard to get used to. For folks coming from Adobe, I find Inkscape the easiest for design. I would use a separate program for cropping, I don't have a great recommendation for that.
I actually use GIMP regularly these days, I found Scribus harder.
Yes, Inkscape is more friendly. It doesnt follow the Adobe paradigm, but it's pretty quick to learn and is closer to the Adobe layout than other software.
The only thing that's kinda funky in Inkscape is cropping, which is done via "clipping", using another polygon to mask the component below. The selectable image stays the same size (but mostly invisible), making automatic alignment kinda annoying. However, thats for bitmap images, and Inkscape is meant to be vector-first, so that's not the end of the world.