1) No, it is not possible. However, you can create a new local user and copy the profile of the domain user into the local profile. This will not copy registry settings unique to that user though, so it is possible it will not be 100% identical. You could comb through the registry, but that would be difficult at best, impossible at worst.
2) No, it is not safe. I cant give you a definitive answer, as there are many factors at play. The logon cache policy, the password policy, and some others. By not creating a local user, you run the risk of headaches down the road.