welcome to healthcare magic forum
face and hand 's skin expose to sun ,dust ,dirt,pollution etc so expose skin is dark
as you have dry skin
so chance of darkness i s higher in dry skin
white spot may be due to sun allergy
or dry skin .
the best thing will work in your case is -apply good moisturizer on face and hand 3 times a day-venusia lotion and use good sun screen like shadows 30 .
drink more water and wear full cloths
if problem persist better to consult dermatologist
i hope i answered your question