3000iu of vitamin d safe for a freshman ?
No it isn't. You need about 600 per day. Remember, vitamin D us fat soluble. That means your body will not just flush out the excess (through urine) so it becomes toxic.
It depends. Have you had your blood level checked? Do you have any medical conditions? Are you doing this on your own or medically supervised? If on your own no; over dosing. Start by having your blood level checked.