The sales staff you encounter when you walk through the door has likely been schooled to pass on the message that the price is the price and they will not discuont. Often the key to creating the desired price movement is to be able to get to a manager who has the authorization to make these decisions. This can be tricky especially if you don't want to upset them too much.
Many of our new home buyers are absentee owners that are having their new home built while they live in another location. We offer the service of advocating for them by monitoring the building of the home. Periodic visits to the construction site to take pictures to be sent to them is appreciated and it keeps the buyer a little closed to the process.
Hope this is helpful.
You can negotiate the cost just as you can on a normal sale (and as in a normal sale, sometimes the seller gives a little, sometimes a lot and sometimes nothing).
I would have the property inspected. If the seller says I will fix that later, make sure you get it in writing.