South of France Travel

(2) WHAT IS A GOOD WEBSITE TO CHECK TRAIN SCHEDULES?
http://bahn.de This is actually the German Railways website, but it has the timetables of all the major railway companies in Europe loaded, and is very user friendly. The French railways site is http://sncf.com but that is not so easy to use.

There is a station at Charles de Gaulle airport which has direct high speed trains to the south of France. I looked at some train times. It would take about 5 hours by train from CDG to Marseilles, arriving about 19:00 or later, so if you can find a suitable connecting flight that would be better.

(3) DOES IT GET DARK THERE THE SAME TIME AS IT DOES HERE IN SEATTLE?
I've no idea when it gets dark in Seatle, I've never been there. But in the south of France, in April, I would expect it to start getting dark around 18:00. There are websites where you can look up more exact times.

(6) DOES THIS SEEM LIKE A REASONABLE PLAN OVERALL?
Yes

According to what I remember of geography class (a VERY long time ago), the times of sunrise and sunset depend on the latitude. Surprisingly enough, Seattle and the south of France aren't at terribly different latitudes. In April, however, especially early in the month, you'll be close enough to the equinox that the difference would be insignificant. One other minor twist is that by April, we in the U.S. will be on daylight savings. I don't know about Europe, but I bet someone around here does.

Summer time runs from the last Sunday in March to the last Sunday in October, so in April France will be on Summer time.
France is due south of Greenwich, but is on Central European Time (=GMT+1). So in winter, it is already approximately +1 hour up on solar time, and when it is on Summer Time it is approximately +2 hours up on solar time. So the sun won't go down until about 20:00. But it will start getting dark some time before that.

It sounds like you have already booked the flight to Paris, is that correct? When you mention the flight connection options to Marseille, are you talking about connections on the same or code-shared airline, so that your luggage could be checked through and you could possibly book it all on one flight record? That is the easier plan. If you book CDG-Marseille on an unrelated airline, then you won't be able to check luggage through and the airline won't take any responsibility to put you on anther flight if there is a delay.

Simliarly, most TGV train tickets purchased in advance are not refundable or changeable, especially after the departure of the scheduled train.

Driving the autoroute (with tolls) is otherwise like any other divided highway. See also some tips and road signs at http://www.ricksteves.com/travel-tips/transportation/driving-europe-tips.

To find out what time the sun rises and sets, I use http://www.timeanddate.com/sun/france/marseille?month=4&year=2015. I find it very helpful, I have been looking into car rentals, picking up and dropping off at different place. I am finding it very expensive. Might be worth returning car at same place and take train to Nice. Have fun.

(1) Sites to see in radius of 2-3 hour drive: Pont du Gard, St. Remy, Roussillon, Nice, Villefranche-sur-Mer, Eze….many more towns. Just drive the coast! We also stayed in Carcassonne, which is a great walled city west of Marseille, you would find it to be a nice day trip for you. If you drive, take a bus into Monaco! Would not do that city again in a car! whew! Yes, there will be tolls, all through France. No problem, just carry some Euro's! Enjoy sounds like a great trip!

Avignon and Aix en Provence which I consider to be one of the prettiest French cities after Paris. Also, visit Cassis (which we did while staying in Marseille) and take the boat ride from there to view the calanques (massive while cliffs). In Marseille, we took a ferry to Chateau d'If, but that's not a "don't miss sight."