Normandy and Loire

Your itinerary looks fine. The St Pierre des Corps train station would be a good drop off point for the car. There are several car rental agencies adjacent to the station. Its close to Amboise and has frequent TGVs to Gare Montparnasse in Paris.

Definitely be in Paris the night before your departure. If you are going to take the RER to the airport, then stay at a hotel close to an RER B station. If you want a fixed rate taxi, anywhere in central Paris would work. I've a preference for the Latin Quarter, the Marais, or St Germain des Pres. Perhaps have your hotel arrange the taxi when you check in the evening before.

Looks good, we have done both Normandy and the Loire.
We stayed in Blois in the Loire, it was nice.

I understand the Bayeux Tapestry is now in England, so you may miss it. Too bad, it is amazing.

My only comment is that if by "the Caen museum" you mean the Mémorial de Caen. And if you are interested because of an interest in WWII history and the Battle for Normandy, I would argue there are many, much better museums in Normandy to visit (the one right in Bayeux on the periphery road is one of the best). I really don't know why RS pumps up the place in Caen so much, but it is way out of proportion to its worth. I would spend the time driving from Rouen to Bayeux visiting many other places. You will drive right through many important locations related to the battle including most of the British sector. The Abbaye de Jumièges is also an amazing site to see en route, and Honfleur is a very short detour.

dms1709,
All sounds good, except I wouldn't spend my time in Caen. do a forum search about the Caen WWII museum and see what the opinions of others are. There are many smaller museums closer to the DDay beaches and in other towns that seem to be more relatable (IMO). And on the drive from Rouen to Bayeux, take D982. It follows along the Seine, a lovely and peaceful drive, and along the way it gets you to the Route des Abbayes. There are a few Abbey ruins that make a wonderful stop. I would pick the Jumieges Abbey ruins. Stop for an hour or so and enjoy the ambience. Rick hasn't brought them up (unless he has more recently) and they are really worth seeing. Plus, the drive takes you through the small town of Villequier, where there is a small museum dedicated to Victor Hugo, who spent many summers there.
Glad you are seeing Rouen...it is too often ignored and is well worth a stay.

This looks like a good plan, and I agree that St-Pierre des Corps is a good place to return the car and get a train back to Paris.

With respect to other posters' opinions, I thought the Memorial de Caen was a very good museum, focused broadly on WWII in Europe and not just the Normandy events. A highlight (or lowlight) for me was hearing the recorded voices of the French generals about to surrender ("armistice"), trying to justify their choices and discussing their individual plans to relocate. It's big and immersive, and the postwar exhibits were less compelling for me. If you had less time in Normandy you might not want to spend so much at the Memorial, but with three nights in Bayeux and another at MSM you'll have plenty of time to see the rest.

The Bayeux Tapestry is a wonder, and I hope it's back from London by the time of your trip. Have a good one!