This is a common question with countless answers.
The first place to start is to determine the zone (or zones) of the property in question.
Zoning Ordinance (Chapter 402)
If it is NOT in a Shoreland Zone then refer to Article 5 of the Gray Zoning Ordinance (Chapter 402) and especially Table 402.5.3 Table of Permitted Uses will show you what uses are permitted (or could possibly receive conditional approval).
Article 5 also includes Table 402.5.4 B - Building Construction Spatial Standards that will show you the dimensional requirements of each zone, (ie minimum lot sizes and setbacks).
Shoreland Zoning Ordinance (Chapter 403)
If the subject property IS in a Shoreland Zone then you will need to view the Shoreland Zoning Ordinance (Chapter 403)
You will find the land use table and dimensional requirements in Section 14.
Once you have specific plans, set an appointment with the Community Development Department at 657-3112 to discuss the details.