Duplex Conversion to a Triplex Questions

[Sawyer Blumhardt]

I am looking at a duplex that can be "easily" converted to a triplex in Aurora, Colorado. I plan to owner-occupy the smallest unit after conversion and rent the other 2. I have a few questions:

1. I don't know anything about zoning laws, fire code, etc.  What could possibly be a problem when converting the one unit into two smaller units.  Where can I find answers to zoning or any legal questions for my area?

2. Utilities are currently metered as a duplex so splitting util. for the 2nd and 3rd unit would be a pain but if we live there its no issue. when we move out is it even legal to split utilities between two units of different size?  Can i just include it into both rents and technically pay them myself?