Is weird numbness and tingling on the left side of your left hand a symptom of impending heart attack?

Probably not. Arm pain that radiates (travels to) the hand and particularly the fingers is usually not heart related, but more likely to be a pinched nerve in the neck. The is referred to as as cervical neuropahy, if it comes from the spine, or brachial neuropathy, if it comes from lower down. I've seem this happen if someone leans heavily on crutches they have been using for a sprained knee.
Sometimes. Sometimes it is heart related and sometimes it is a pinched nerve. See your doctor.
Probably not. Pain or numbness in the left arm or hand can be associated with heart attacks. However, there usually are other symptoms such as chest pain, shortness of breath, and fatigue. If you just have numbness and tingling it is probably related to pressure on the nerve either in the neck, the elbow, or the wrist areas.