If you have over-improved the unit for the market, it is highly unlikely that you will reap a higher rent price...the market just doesn't support it. 

My partner works in finance and I have been managing high-profile construction projects for about a decade.

If you are using an agent to rent your property, then his MLS may or may not syndicate with other websites such as Zillow, Redfin, Homes, 'Apartments.com, Trulia, etc....you can check by typing in your home address on each of these websites to determine if your property was syndicated or not.7 If it wasn't syndicated, then yo will have to post it up individually on these websites. 

I received a quote from a broke that mentioned it will be ~$30k/unit (seems high), which should include adding washer and dryer units to the apartment. 

Sometimes they are noteworthy and sometimes not.I don't think it's reasonable to charge people two application fees so it's probably just best to get your leads through Zillow and then have them apply on a different website to screen them.

For example our bridge loan product is ok with your debt to income being to high at the time of purchase as long as the debt to income will be low enough to qualify once you rent (or sell) your current home. 

I think if when rates dip into the 5's or high 5s the market is going to really explode.

And of course price usually is the issue if its priced right things sell  priced to high they sit at least for single family parcel. 

Their website shows a downtown Seattle address that is likely a condo and not a business office.

I use TenantCloud and when I make a listing on there it actually pushes it out to a ton of website.