Mazda 626 1991 Problems

It’s an old car and you have to expect some wear and tear over what is now coming up for 20 years. Smoke on a cold start isn’t necessarily oil related; it is often condensation and nothing of concern. The oil leak is probably just a gasket that has hardened or split and needs replacing. If it is burning oil it could be due to wear in the valve guides or it could be worn piston rings or wear in the bores. If it’s not leaking a lot, just leaving a spot on the driveway, and it’s not using much oil I wouldn’t be too worried about it. The worst-case scenario would be that engine might need reconditioning.