Looking for some itinerary advice on trip for spring

I'll limit my replies to only a couple of your planned visits. For the Loire, pick one place to stay. Especially since you have a car, most of the Loire is easily reached as day trips, with proper planning. We stayed in Amboise and found it convenient for seeing the chateaux in both the eastern and western parts of the Loire.

I think you mean Mont St Michel. It's certainly worth a night's stay.

You propose less than a day, and orobably less than a half day, not even staying over night for the whole D Day area. While you can see a very limited amount in that time, I'm afraid any history buff would be disappointed by the amount you wouldn't have time for. If possible, try to at least spend a night, and hopefully arrange a guided tour.

In the mean time, you have lots of time to read through a few guide books to see exactly what you want to see and do in each of these places.

I don't understand your Day 1. You're flying to Toulouse, but where are you leaving from? You're not even staying one night in Toulouse and you want to go to Carcassonne on Day 1?

Toulouse, the pink city, deserves at least two full days to explore it.

A taxi from Toulouse to Carcassonne will cost you a fortune. If you take the train, it's an hour's journey and less than €20.

I don't know what you want to visit near Carcassonne on Days 2 and 3 (Cathar castles, Corbières vineyards?), but keep in mind that without a car you won't be able to go anywhere.
Speaking of which, I don't see the point of staying more than one night in Carcassonne. If it's for the photos, a few hours are enough. For the historical aspect, know that what you'll see (the Walt Disney castle aspect) dates back to the 19th century. The medieval city was rebuilt starting in 1852 and is nothing like it was in the 13th century.

If you're looking for castles, you'll find some real ones in the Dordogne; I've listed over 50 on this map.

https://www.google.com/maps/d/edit?mid=1OdPOg8AgsNn0Jlv1cNHkujaWv9p_Jpc&usp=sharing

My itinerary advice for these first days: stay in Toulouse for three nights, with a day trip by train to Carcassonne.

Puy du Fou (not Pou du Fou) is an amusement park well known for its historical-medieval show and there's nothing else to do or see nearby. Is that what you're referring to?

• Yes I'm interested in the (Cathar castles) --- I'm very interested in as many castles as possible, and I will 100% rent a car for everything but Paris. The main reason I'm thinking of being in Carassonne 2 days is to see it both at night and during the day vs taking a train there twice, but this is useful information.
  

Sorry yes I meant Le Puy du Fou~ it looks insanely cheesy and I'm interested in how weird it will be. 100% wouldn't spend money at disney but if I can go somewhere domestic and interesting I'll check it out.

Your map is insanely helpful.

Cheesy, undoubtedly! It's also the best show in the world according to its organizers. It's a matter of perspective. I never go to these things unless I have to take children.

Regarding the Cathar castles, you can find a map here:

https://www.audetourisme.com/en/see-and-do/not-to-be-missed/royal-fortresses-and-cathar-country-sites/visit/

Rent a car from Toulouse, but you'll have to make some choices, two days is too short to see even a small part of it
The difficulty of access being the basic principle for building these castles at this time, some are not accessible by car, you'll have to walk.