Yes on the "q" in cinq. In French I we used a little story to teach the first 5 numbers in French. It was about a mother cat and her 2 kittens out in a boat. A big wave came, the boat tipped over and "un, deux, trois, quatre cinq." (cat = get it?)
"à la main" usually means "by hand" as in "it was fabricated by hand." "on each hand" = "de chaque côté." The best bet here for "5 fingers on each hand" would be "sur la main." (OR "une")
"d'une part" = on one hand is in something like "On one hand he wants to go but on the other hand he has to work.
Sra (aka Mme)