Or could you rent it to another business which would drive customers to your restaurant?

Are there any laws, customs, etiquette, or general rules of thumb I should follow as a wholesaler?

I would recommend just continuing with your business as you otherwise would, and when you have a couple new deals that those buyers might be interested in, offer it up to them first.But:- I wouldn't look for deals they specifically want, unless they are deals you'd be willing to do otherwise;- I wouldn't customize a house for them unless they were willing to put a large enough deposit down that it would cover having to remove all of their customizations should they not follow through on the purchase;- I would pre-qualify them as you would any other buyer, and not give them any preferential treatment.In other words, go into the deal assuming the worst case -- they will ask you to do a lot of customizations and then back out of the deal. 

Given your PM background I'll take on time, under/on budget and a satisfied customer (YOU!!!

No issues or complaints from my customers.

But it's all (repeat) business.A tenant is a customer.

Tenants are customers, customer service is what keeps people and retention is customer service driven.Prompt service, prompt maintenance, Clean building, good looking exterior and ground maintenance.Give people pride in where they live and they will stay. 

Welcome @Joel Schilperoort.Where are the properties you sell/buy for yoru customers?

Aggregating data from public information is typically better to buy or rent from commercial providers unless you want customized data fields, highly targeted leads, compiled lists or response lists (prospects test have responded to others' offers). 

The " by the push " is the only way we do plowing , ( been doing it 33 years)  snow gets deep , we bring out the loaders and the customer breaks out the check book .