Want to Buy First Home as Rental Property Next Yr- Advice?

[Kate Myres]

Hello!

I have a rough idea of what I want to do, but no experience or expertise. 
I live in a LCOL area (Arkansas) in a small town rapidly developing into a desirable suburb. I am currently in a great living situation splitting a low rent with my boyfriend and do not have plans to leave this situation. I want to buy a single-family home for about $100k and rent out for about $1k/mo- reasonable prices for the area and not hard to find a house in good shape for this price. I am not sure what rate I would get on a mortgage, but I should be able to afford the monthly payment without tenants, and have positive cash flow (barring needing repairs) with tenants, which is what I am after. (If numbers are needed- gross income is approx 5200/mo, no car payment, rent $200 ($400 room split with bf), student loan payments will be $420/mo after deferment is over, no other debt. FICO score currently 717- all on time payments but short history and student loans not yet very paid down)
I am originally from Los Angeles. My parents still live there, but my dad lost his job this year at 64yo- neither of my parents intend to reenter the workforce and they will have to move soon as they cannot afford their mortgage payments- but they would not have trouble affording a mortgage here in Arkansas (though I don't know if it will be hard for them to get one with no jobs? Off-topic..). They are considering buying a house here, but my mother wants to rent first to see how she feels about Arkansas and look at houses.
I am intimidated by the prospect of becoming a landlady and thought that it would be a good opportunity for me to ease in to it by renting to my parents as my first tenants. (Neither one has had a missed or late payment in their lives.) Depending on when I buy the house- thinking next summer- I may not have 20% saved up, and it is a possibility that my parents may be able to give me several thousand dollars to make up the difference on the down payment, and I would not charge them rent for the number of months that corresponds to the amount they give me ÷ rent. 
It is also a possibility that a few years down the road, my boyfriend and I may move into this home to start a family before moving on to purchase and live in a larger home.
Questions:
Do any of these potential uses for the home change anything tax-wise or in the process of applying for the mortgage? For example, if in the first year I own the property, I collect no rent (only the sum from parents)? I assume I would declare that this property is for rental purposes while applying for the mortgage, regardless of whether my parents live in it for a year or if I live in it at any point in the future?
When I see these little "Calculate your mortgage rate!" widgets on websites, the results disappear when I change the loan amount to 100k or below- will it be more difficult to get a mortgage on a more affordable home? Should I expect a higher rate? Should I expect that I may need to put even more than 20% down?
What do I need to consider that I have not even thought of?

Thank you so much for taking the time to read this!!!