Should my boyfriend still use a condom even though I'm pregnant?

Usually not needed. The two reasons for condom use are pregnancy prevention and std protection. No need to worry about the first! if neither of you have other partners, stds should not be a worry, and you can best decide about that. Occasionally, we advise condom use when a pregnant woman has strong contractions after intercourse, some of which may be due to chemicals called prostaglandins which are found in semen.
Depends. It depends on why you are using the condom. If it is merely a birth control method then it would not be necessary during pregnancy. If there is a possibility of a sexually transmitted infection, then condom use would be recommended.