Traveling by train for my specific itinerary?

Hey guys, I know the topic of Eurail Pass is brought up a lot, but after spending hours on the Internet I still couldn't figure out all the answers to my specific travel plan. Here's all the train trips that I need to take: Paris CDG - Aix-en-Provence (TGV) Marseille - Milan Milan - Venice Venice - Florence Florence - Rome Rome - Paris (night train) And here are my questions, 1. If I buy a French-Italy Eurail Pass, does that pass work for all the above-mentioned trips? 2. How do I figure out which trips require reservation and which ones don't? 3. For those that require reservation, how do I make reservation in advance?
4. For my specific itinerary, would you recommend me buy a French-Italy Eurail Pass? Or which part I should buy a pass and which part I should buy point-to-point tickets? Thank you so much!