1) How long has he been in the building industry: how old is his PRESENT Company?

Get some information on their history. Even if they've been in the "field" for years, it doesn't necessarily mean they have experience running an organization with multiple projects going on at the same time.

2) What is the price range of their homes?

Make sure they have the ability to "work outside the box".

3) What areas do you have available for construction?

Are you able to choose your own location?  Will they build on your lot? Find out what schools, shops, areas, are available in relationship to their building sites.  Are they're any restrictions in these areas such as fences, pools, etc?

4) What products and procedures do they use?  A few examples to look for are:

What brand of Furnace and Windows?  Energy efficiency and even more important; do they custom frame or us pre-fab?

5) Are choices available such as?

Siding color
Roofing
Flooring
Cabinets
If so, are there any limitations?

6) How much does it take to get started?

Do they offer Financing? What is their draw schedule?

7) Are you required to use their provided plans or can it be custom designed?

This question can uncover any limitations they might have.

8) What is their Timeline?

Ask about their scheduling method and if there are scheduled walkthroughs.

9) Where can I see some of your homes?

Check not only they're newer homes but older ones as well.  See how they have held up over the years.

10) How assessable are you and your staff throughout the building process?

Make sure the last time you talk with them ISN'T when you give them your down payment!