Whether you find one lot or 10 lots to turn into one, the process is still the same. The only difference is dealing with one owner or multiple, and sometimes that can be more difficult that the Planning and Zoning process.
Once you find a site you like there is a lot of research you can do before getting the lots under contract, unless there is competition in the area for the same land then you may want to consider getting purchase agreements prepared to tie up the land.
You can contact the local planning & zoning office to find out the current zoning and also discuss your thoughts to see if they will support your plan. The P&Z staff makes recommendations to the Plan Commission, City Council or Zoning Board, whichever group votes on zoning in your area.
The Planner can outline the zoning process as well as the approval process to follow that gets your construction plans approved. That process will likely involve review of site plans, utility plans, grading plans, erosion control plans and storm water plans, etc.
I tried to be somewhat general because different cities do some things differently. Your goals are similar to ours with new construction and and the need to rezone and obtain planning approvals is similar all over the country. The difference is what they require of you (the developer) to get there.
Good Luck! and let me know if you have other questions.