Can the developer, through restrictive covenants or sales contracts, control my choice of builder or real estate agent?

Can the developer, through restrictive covenants or sales contracts, control my choice of builder or real estate agent?

Not in most cases.  However, a developer may lawfully refuse to sell directly to you and instead require you to purchase a lot and home from a particular builder.  As to real estate agents, a developer may include the agent's commission in the home's purchase price.