I did just what you are talking about starting about two months ago and am almost done now. I would suggest not going to far. Paint it the same color if possible so you don't have to paint all the little parts that are hard to get to. Thats takes almost as much work as painting the outside of the car. I took hood, front fenders and back hatch off which was required for changing the car from white to red. If you keep it the same color you can leave it together except the front fenders which will have to come off to weld in some patches where they rusted. You could do them on hte car but there are areas in back that need to be cleaned out and treated so the don't rust som more. Put them back on to paint the car.
The fenders were fairly easy to fix but get a cheap fender from the junk yard and do all your practicing on it and not your car. Things don't work right the first few times you try body work and welding. I also used it for patch material since I could find a curve to match almost any part I needed from it. (best $10 dollars I ever spent.)
I avreaged about an a hour or so a day on it and it is starting to look good now. I would recommend you use a base coat and clear paint system. I tried the single stage paint and it is to hard to buff out and remove all the scratches. I am still buffing.
The rusted out areas hardest to fix were the rusted out Dog-legs in front of the rear wheels and the battery tray area in the engine compartment.
It sounds like your car is in much better shape then mine was. I counted 31 dents in the roof alone not counting the dents inside of dents. So it can be done it just takes time and a lot of learning. Go to the Autobody forums and start reading. That has most of the info you need to for painting and body work. http://autobody101.com/forums/index.php?
Good Luck,
Jerry