Single Family Building/Development Modeling Resources??

I will answer the question from a home builder's point of view and then let you, or anyone else, follow-up with further questions or questions on land development, which is a completely different business.

1. Think of home building similarly to manufacturing.  The decision to move forward on signing up for lots in a new community is very simple, whether you're at a national production builder or a local builder.  It effectively boils down to: I can build a home for $X, sell it for $Y, make $Z which is %Z profit margin.  As long as the builder feels they are making sufficient profit margin and they have the capital to move forward, they are happy.  Even then, in some environments when they aren't making sufficient profit margin they may still sign up to 'feed the beast.'  Because in home building, similar to manufacturing, if you significantly slow down, or shutdown, the operations for an extended period of time, you will lose human capital.  Your superintendents, sales, and so forth will go somewhere else.
2. Builders don't have large scale projects.  Conceptually Builders are buying 'finished lots' (lots ready to build homes on) from land developers and then building a home on that lot.  They have 'lot takedown schedules' where they sign up to 'take down' (purchase) X lots per period (monthly / quarterly) from the land developer.  This adds to their vacant finished lot inventory and they build homes as they see fit on these lots.  Before they begin building in a community they will have an idea of the product they want to deliver and yes, they will get 'take-off estimates' from their architects when designing and then formal bids from subcontractors before they start breaking ground to build the home.
3. It varies widely depending on the type of product you're delivering, the market you're in, and etc..  A private, semi-custom home builder who focuses on small volume in a local market may have 60%+ gross margins.  A public, production home builder who focuses on massive volume across the nation may have 20% gross margins.  Then you have everything in between.  Also consider margins expand and contract at various times across the industry.  So margins peaked in 2021 and are down in 2023.  But also remember that build times are important to home builders because it measures how fast they recycle their capital to build the next home.  So if your build time went from 12 months in 2021 (because of labor shortages, material shortages, etc.) to 9 months in 2023, that's meaningful to your bottom line even if margins compressed.  Think of it as a return on equity calculation.  For example, you may be okay with 20% margins if you can build a home in 6 months versus 30% margins if that home takes you 12 months elsewhere.
4. I don't understand what you mean by development and my best guess is you don't really understand the difference between land development and home building.  But would start with the easily accessible things like YouTube, 10-Q reports for the public builders, and so forth.  If you're interested in the land development side, I think there's a YT channel called "Land Development 101" that will give you a brief overview of what all that entails - which is completely different than home building.