Developing Help

I am considering purchasing and developing a 1.5 ac lot in nashville, tn. It lists for $500k with tax appraisal on the land for 350k. There is a single family building that can be converted into an office, but I want to bulldoze it and improve the land. The property is zoned commercial as its on a high traffic street. I want to build a small apartment complex on it consisting of two four unit complexes. I just wanted to know that if the property is zoned commercial for a low rise office bldg, should it be difficult to change the zoning to multifamily use? Also, developing scares the crap out of me as I am a newbie. Can anyone tell me more about the process (maybe give a step by step generally)and what kind of fees can I expect for an architect to make drawings of the small apartment bldgs? I know i need to propose to change zoning but when do I make the offer on the land in the process? Thanks.