New Home Construction & Value of your Realtor

Building a home (custom or "large volume" home) and discussing the details without your Realtor present is not a good way to utilize your Agent. This leads to a ton of issues that rarely get worked out and leave a bad taste in the mouth of the buyer principal. If your looking at building a home, lean heavily on your preferred Realtor. Every step of the process needs documentation. Work orders, modifications, future promises on upgrades, notifications to inspect at a given level of construction all fit into the type of thing a good Realtor does throughout the escrow. It is a good idea to check on the progress but getting into a dialogue w/out your Realtor knowing about it (and documenting the discussion on paper with signatures from both builder and buyer) can lead to trouble at the end.
Last, and this is huge for you first time buyers - DON'T CLOSE UNLESS YOUR HAPPY WITH YOUR FINAL WALK THROUGH!! If you are certain the items on the final punch list could be left incomplete and you would be ok, go to closing and fund that project. BUT if there are still some relatively large 'to-do's' on that list do not fund the closing. Go ahead and digest having that Thanksgiving Day meal at Luby's (a local cafeteria) or paying the extra sur charge at the rental property. If you truly want it done and done right, hold your ground and wait to close. You will get everybody and their proverbial dog focused on your home.
In a new neighborhood with a high volume of homes being constructed, the "Super" (lead General Contractor of all construction) gets so overwhelmed with all the details. Having knowledge of what was written and agreed to plus any heads up on poor workmanship helps him and the rest of the neighborhood.