Converting a store front to an apartment for the first time. Suggestions Please

I have a 1600sq ft store front and want to convert it into apartments.  The rest of the building is 4-2bdrm apartments.  I need to get drawings of the plan for the town. 

My two questions are:

1.Where do I start?

2.Do I make 2 small units or 1 large 3 bedroom

FYI, parking here is very limited

Thanks