It really is the nature of building, it's a process, and not a perfect one at that.

By it's nature you are almost assuredly talking about bigger deals and more money. 

I am naturally trying to discover some formula to see what the ROI would be so that I can calculate (if everything were to go well) how long/far off are we from being financially free (will be working on 5 and 10 year goals soon).

The nature of your post lends me to think that you might want to focus on taking action and making it happen. 

I am concerned only with stable low vacancy cash-flow, and don't mind having no appreciation.However, since this is my first property, and I've worked so hard for this cash, I am naturally really afraid to move forward and pull the trigger, due to my lack of experience.

I am naturally an aggressive investor and strongly believe in the power of leverage.

And I found its  more of type (chrome, nickel, polished) than which one, other than the cabinet pulls - that one was “hummm what do I do”.By nature I always need help in choosing wall paint or anything that needs to coordinate.

If the second purchase can be very worthwhile, it might be worth those consequences, if not, I'd work on improving credit score to get a better rate (but keep in mind, in the time that you improve, it might naturally go up anyway and be a wash!)

The vast majority of residential structures built today are still naturally ventilated through the stack effect.

Once the turnover naturally occurs bite the bullet & get the unit up to the best standards & maximize the amount of money you can get for it.