Can poor leg circulation cause formication?

Possibly. The sensation of creepy, crawly insect like disorder is more typical or superficial nerves responding to something topical such as a lotion, dry skin, etc. "poor circulation", presumably your refer to arterial, causes claudication, or a deep muscle ache. At your age, unless your have diabetic neuropathy, prior traumatic damage to your skin such as a burn, i would doubt. Ask your doctor to look.
Not usually. Causes of formication include normal states such as onset of menopause (i.e. Hormone withdrawal). Other causes are medical conditions such as pesticide exposure, [2] mercury poisoning, diabetic neuropathy, skin cancer, syphilis, lyme disease or herpes zoster. Formication can also sometimes be experienced during high fevers. Itching, tingling and formication often occur when surfacing from a dive.