You can get a new cert with the correct names. You dont need the cas array name on the cert, only for web services Exch has.
You only have 1 server so decide how you are going to have CAS deployed in the end, i.e 1 server or 2? You can have CAS on the same role with a CAS array still, just means you can;t use WNLB therefore have to have a HLB.