IMHO, this is terrible advice: "At the top of your listing, ask that potential guests send you a note inquiring about availability before they try to book."
Just think, if two listings are side-by-side the potential guest is going to send a note asking if it is ok to book to one and Instant Book the other. Guess which listing is going to get booked in that scenario.
And this seems penny-wise and pound foolish: "Every time I stay at a real hotel, I make a point to grab the mini bottles of shampoo and conditioner."
Travel size shampoo and conditioner are $1 per bottle at Walmart or $0.17 from Amazon in case quantaties.