I am in FL too and it’s any repair costing $1,000 or more requires a permit.
As for roof repair, I’ve never pulled a permit for just a small repair; new roof - 100% permitted every time.
Electrical panel ... this is a tricky one. In many cities in my area, when you update the panel, they require you to do a full electrical update. This changes a $1,000 panel swap out to a full blown $10,000 electrical update ...KNOW YOUR LOCAL CODE. So to answer your question on this one, it depends on what the area demands. If it’s a higher-end flip, then yes, permits. This DOES open up a can of worms because if you pull an electrical permit they will see the other renovations and you will need the full package of permits and since it’s an investment property you can’t pull owner-builder permits and will need to use a GC thus adding even more to your expense. I like full permits and I market my flips as being fully permitted under a GC because I know most of the competition doesn’t do this.