Save half the commission when you sell by using Realmart or a similar online MLS listing service, for a flat fee of a few hundred dollars they put you on the MLS and then realtors will bring buyers to you without you having to pay a listing agent of your own.

Invest all of the $25k loan into ETFs (spread out to achieve some dollar-cost-averaging) and continue to invest 50% of my income (minus the debt servicing cost).

Did you encounter any opposition or criticism of their services from an attorney or accountant?

I am not sure if they service where you live but I am sure he can offer some advice. 

Some consumer sites have better search functions and are certainly improving their services on a regular bases.It all depends on what you are looking for.

One idea that comes to mind is to find a property where you can add appreciation by making improvements to the units or property.

With a target customer segment in mind, then you set about developing a product or service that your customer is willing to pay for that consistently meets their needs better than the competition.When we bought our two SF rentals, I used that same approach.  

They even cashed me out a little to make some final touch improvements.  

Also if it's currently occupied then you can perhaps count 75-100% of the income towards making the debt service payments but check with lender because I'm no expert on this!

This suggests that they are going to hang on to the tradeline on the books and service it themselves.