15.Can people see which charity is given a particular voucher?

No.  We regard that information as private to the donor and we do not give it out.  When someone uses our 'check-a-voucher' service they are only told whether the voucher has been used yet, not which charity it has gone to.  We may publish or give out general information about which charities have been receiving donations but it will not link any particular donation to a particular charity.