Is there some type of retainer agreement where she leaves a deposit and if after she gets back from vacation decides not to rent from us that we can keep the deposit?

tell them, you pre-screen applicants, which includes getting proper verification by seeing photo ID before you show new tenants the house, and you have written down contact and names and phone numbers of those applicants on your "appointment sheet "because you also want to also need to retain the information for Fair Housing Law" and keep that information for 2 years.

I'm worried I won't be able to attract and retain quality tenants.How would you handle this? 

A good idea is to have ceiling fans in each bedroom also, it cuts down on hvac expenses, and even if you're not paying utilities it helps to retain students when they have low utility expenses in your home. 

As a result my decision is usually to limit rent increases and retain tenants.

You choose to take a risk that you will be hit with fair housing and discrimination complaints, fees, and penalties, but you think that risk is worth the benefit you gain by retaining complete control over tenant selection.

For example you could put in a retaining wall on steep slopes.

Here's what our rental agreement has to say about repairs:REPAIRS.Tenant agrees to notify Landlord of needed repairs to premises in a timely manner by telephone and/or in writing.Tenant agrees not to repair their dwelling or anything belonging to Landlord without prior written consent of Landlord.Landlord retains the right to determine how and when the repair will be done, in accordance with federal, state, and local law and codes.If the need for repair is not due to damage caused by Tenant and/or their guests, Landlord agrees to pay for the repair.If the need for repair is a result of damage done by Tenant and/or their guests, and not that of ordinary wear and tear, Tenant agrees to pay for the repair.Landlord may decide to remove or replace an item, instead of repair.

Again, peculiar case.I have a bad feeling this will ultimately end in my having to retain specialized legal counsel to cope with a lawsuit of some kind.

The issue of self management of retaining the services of a professional is one of time and cost.