The white is mandatory for clinical's only. I have never seen them enforce leather like or mesh. Just beware, if you get bodily fluids on your shoes (Which you will for sure) then mesh will take it...
Semester 1 by far. You will have days off. Semester 2 has been brutal, classes 3 days a week and clinicals twice a week. Try to get afternoon classes if possible, they seem to be easier. Don't worry...