Exactly, when people mention losses saved by superconductors they don't mean to improve the current grid. It's to route power from the always sunny side of the planet.
No. Sorry the Mediterranean Sea separates Europe from Sahara (as well as several countries) and you can't do this practically by any means. Europe doesn't own the Sahara.
The main problem with installing solar in the Sahara and transporting it to Europe is the political instability of the region. Laying cables across a sea or ocean is already routinely done.
There's communication cables laid across the sea. There's no examples I know of High Voltage transmission with enough power to operate Europe. It's not only the instability of Sahara, but laying a cable across the sea for the transmission of enough energy to power Europe would require defense of the cables. A submarine could otherwise attack the grid and take Europe offline. This is unpractical on a lot of levels and hand-waving this as a reasonable solution is silly.
You can't run Europe on a single 1000km line running out of the Sahara over the Mediterranean. Period. Not only would a sea cable need to follow the surface of the bottom of the ocean (therefore the line would be much longer), it would experience significant power loss as it gets stepped down from higher voltages as it distributes across Europe. It's not technically feasible at all. You would lose anywhere from 20-50% from transmission. No joke. Resistance happens. A superconductor would fix this problem. You wouldn't have to send power over dangerously high voltages to save power.
Semiconductors don't have infinite capacity. You assume that the superconductor is also practically free. Even them, building a net is still very expensive