Lake Como to Provence tips

fly to Italy . . . . before heading to Paris for our flight home. . . . Is it reasonable to drive from Lake Como or Varenna to Provence?

Yes, it is reasonable to drive that. Except, I presume you will be renting a car when you land (at Milan?), but where will you be returning it?
Renting a car in one country and returning it in another usually attracts a large surcharge. Driving into France then returning the car back in Italy will be a lot cheaper.

I agree about renting a car in one and driving to another country (expensive). Look into taking a train from Milan to Aix or Nimes (see how much it is, and if it fits your schedule. Check Trenitalia - you will probably have to transfer at Ventimiglia where Italian trains stop and French trains start). Then rent a car in Nimes. How are you getting from Provence to Paris? Train? You could do this from the Nimes station as well, and return the car before boarding the Paris train. In Provence, it depends what you want to see, but you will want a car because it is very spread out. We stayed in La Isle sur la Sorgue, because we wanted a smaller village stay (rather than, say Avignon or Aix, or even Arles). We spent one day driving among the villages and Abbey de Senaque on Provence's eastern edge, one day going to Vaison la Romaine (north), and making a loop drive of it (one route there, one route back), one day going to Le Baux and Arles, and one day going to Pont du Gard. Where you stay depends what you want to visit and what experience you want from the town. It will be high season then, so you will want to schedule your days around visiting sites first thing in the morning or in the evening before closing. Driving is easy but long. We did not visit cities like Nimes or Avignon - we stayed 4 nights and our priorities dictated other things.

(as an aside, you've now got me googling spanish language schools in Spain for my 15 yo daughter for next summer ;p)

This trip seems to be going really far out of the way to see specific things when equally impressive things are closer by.

1.) Provence is a very large region split in my opinion into 2 very different areas so would need to know which you are talking about. The Cote D'Azur area is in Provence, so are the Lavendar fields and Roman historical cities like Avignon, Orange, Arles ; and then there is also the coastal area around Marseille ; also in Provence.
Given you only have a few days you need to stay in 1 place so have to know more about what you wish to see to possibly recommend a place.

2.) Is the drive reasonable from Lake Como area to Provence.
Well if to the Nice area, Cote D'Azur I would say yes to the more western areas I would say not without an overnight in between.
The big issue though if you rent a car in Italy it will cost a huge surcharge to drop it off in France. Renting a car and dropping off elsewhere as long as in the same country is usually free in Europe or low cost but another country is a different story.

3.) Comparing Menorca, Spain which is a small island out in the sea to a mountain area Lake in Italy is near impossible or could be not more different.
If you were trying to compare Menorca to other islands ; say to Ischia or Capri both in Italy that could be easier done.

Thank you all. I didn't realize that the drop off fee for the car would be expensive.
Will definitely need to re-consider that piece

I will add that it will be quite hot in Seville and your daughter may be ready for cooler climes. I have a friend who teaches a summer course there every year, and he is always ready for relief from the heat.