Customer service has always been good.

There are multiple universities nearby if the college crowd is your customer base.  

If the law says it fine, your broker/agent agreement is in compliance and the customer is OK with it, your good to go.

If it is a geographic market then why not try Ever Door Direct Mail (https://eddm.usps.com/eddm/customer/routeSearch.ac...).  

I'm also looking for a general labor crew: someone to install toilets, lay laminate flooring, screw in odds and ends, and build a custom kitchen island.

We see other companies take management anywhere and I know it is tough to provide the level of customer service we expect to provide the larger the footprint a company has.  

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!!!