Sanding and polishing will remove any orange peel and leave a mirror finish. If you are doing a factory look resto, you may want to leave the orange peel, as they didn’t polish it out.
Most good body shops do polish (at least a bit) to get that perfect look, depends on how much your paying them.
I have used the paint that Rich is talking about and its a good look. I still like the look base/clear better, but that is total personal choice.
Also if you sand through the clear you can just respray a coat or two, sand through the colour and your screwed.
The urethane is a better quality paint then Dupont Centari (acrylic enamal).
Again personal prefrence, but I like PPG paints better for base /clear and their epoxy primer is the best, as I've tried them all. (IMHO)