Along with zoning, if you rezone they may take land for future roads, or some land for park, or you pay school site acquisition costs, etc... You need to start the conversation with your local municipality. Along those lines, just because there is a road there, it may not have adequate civil utilities. If there is no water pipe or the pipe is undersized for the proposed zone, then you may need to upgrade it. Same with sanitary and storm pipes. Also you may need to bring in hydro, gas, tel/cable lines so that can be costly as well (the existing house needs a lot less power than multi-building complex). Some things to think about. Here are the steps I suggest you follow:
1. Go to talk the Planning Department, check the zone online (if that info is available) and see if what you want to build fits the zone. If not you may have to rezone. See if there is a OCP (Official Community Plan) or NCP (Neighbourhood Community Plan). If the City has endorsed a plan that allows the property to be developed to the zone you want, it will likely be easier to go through the rezoning process.
2. Find out if they can refer any architects, if not (at my City we aren't supposed to refer one business over another) check out recent developments and figure out who designed those buildings. Also, obtain a civil engineering firm that specializes in local land development. Each municipality has their own rules and processes so local is key. Don't choose the cheapest as that will hold you up and cost more money up when they don't know the processes. Time is money. I see so many developers retaining one-off consultants that don't know the process and are held up by months.
3. Have your professionals see if what is allowed to be built (with current zone or future zone) is feasible. Run your numbers. As @Ned Carey says, is it even worth doing? The preliminary stages listed above will cost money but you need to start somewhere.
Good luck!!!