buying new home ...need help

My sister is thinking of buying a home in the Bay Area, California.

The developer is building 3 new houses. He is not a known builder.

What should one look for when buying such a new home ?

The builder does not have a web site ...the sale is being done thru a
real estate sales person.

The homes are pretty, have a good floor , good location etc.and that is
the attraction.

Can any one pls help ?

Is there a checklist ?

should she have a real estate agent represent her ?

Normally when one buys from a well known developer one does not need a
RE agent to represent oneself but in this case....the developer
appears to be a mom and pop type....so what to do ?

Thanks
Linda