As a reference, take a look at this string. I've got some photos on there. I crossed a Mottled Male X Buff Columbian female and you can see the f1 results as well as f2 results thus far. Speculation that the original Mottled was carrying silver vs. gold, but nonetheless gives you an idea.
After I get my F1's. What do I breed them back to?
Would it be ideal to get a Mille Fleur and breed to that
If you can stay within your breed that is your best bet. You can breed the F1s together or you could do the reciprocal cross & breed the males from one mating with the females of the other & vice versa.