@Kevin Hu
All condos in Mammoth are zoned for nightly rentals, but there are a handful of complexes that do not allow nightly rentals per their HOA CC&Rs. You can just double check with your agent, but 95% of condos in town are good to go.
A list of expenses would be difficult because each HOA covers different items. All HOA cover your trash expenses, snow removal, and exterior maintenance and insurance. Most cover your water and sewer. Some cover internet and cable, or you can get discounted internet and cable through the HOA. There are a few that even cover your hot water or propane.
Your biggest expenses to account for are HOA dues, Management, and TOT. Then check what the HOA you're looking at already has covered, because that will make a huge difference.
I would personally recommend looking for a unit that either has propane included in the HOA dues, or has a pellet stove (or you are planning to put in a pellet stove). Old electric wall heaters here are really expensive to run in the winter, and guests always crank up the heat. Propane is about $4.50/gal, so it's also crazy expensive to heat a house with forced air. A pellet stove set to a thermostat is the most efficient way to heat a unit that guests can actually understand.