NGTeco 10 PCS RFID Cards for Time Clock TC1 TC2 MB1 MB2

Is this card rewritable? Can we delete the info of previous user on this card and use it for new user?

Do I need time cards? Doesn't the machine record the time in and out without a card?

Do these cards already have codes assigned to them or are they blank?

What frequency does the machine and cards work on?