Utility bills, rental lease agreements, paychecks with home address, address on IRS returns past 5, 1099 and w-2 mail to address, USPS mail records ... are what you need if you push the limit and get audited.

Everyone same loan product, all will utilize as a short term rental.  

Just send the break down of utilities.

Currently Rents out for 1200 per month, all utilities included, cutting my living expenses in half.

The strategy I plan on utilizing once I get through the Winter season is to send a rental increase package explaining why a rent increase is needed, showing comps of current market rents (for instance, using rentometer), and offering a few different options such as a year lease at a reasonable price, a 6 month lease at a higher price, and a month to month at a slightly higher cost.

That's great you were able to save up 35k, which is a fantastic place to start and you can utilize a low down payment mortgage.Denver metro has a lot of great pockets that work for your goals with price and proximity to the mountains and the city such as Lakewood, Wheat Ridge, Arvada, west Denver (west of I-25), Westminster, Thornton and Northglenn.

Sometimes including utilities. 

That may not JUST be confined to the rental amount owed, but rather utilities, late fees, etc BUT that varies from state to state and you'll want to consult your state's Tenant Landlord Act and related laws.

I will honor their current rental agreements but plan on increasing rent as much as 70% (owner was paying utilities too) with the next agreement. 

I've used instagram for the same reasons everyone does (mainly sharing funny stuff with friends) but I've also made a decent little lead generation tool out of it.