I would suggest looking at similar properties for rent, then advertising yours at a slight premium to them and lower until you get inquiries at which point you will be close to the market price.
1.)You talk about your equity making 0-3% a year from appreciation but you have not mentioned the free cash flow from the rental income. This would most likely make this a very good investment to hold and you can invest the monthly cash flow in another area. You would probably have to refi to take any equity out considering you cannot take a line of credit.2.) Rent to own is basically selling an option to buy the property at some point in exchange for a down payment or higher than market rent amount with a portion going towards a potential down payment that is usually forfeited if not exercised by a predetermined date. If you and the tenant could come to an agreement you could then contact a real estate attorney to set up the contract.
Until you have a signed lease and a deposit all comps/ rent estimates are just speculation. Similar properties usually fall into a range and I usually give my clients a basic range from the most recent properties I have rented but the truth of the matter is , your property is worth what someone is willing to pay for it at that time and an estimate is not very useful.