hi keenen and welcome, as far as the 5 rentals I wouldn't concern yourself just yet, unless you have deep pockets and are planning on purchasing all 5 right away, a good mortgage broker and advise from here will guide you down the right path, by purchasing with companies, partnerships, etc.
Our rentals (7) we only take tenants that have a good job history, if they can keep a job they can usually keep up on rent. We also go with our gut, as we have rented to tenants that have good jobs but we felt a bad vibe when they applied for the apartment, we rented to them anyways just to find out that the vibe we felt was right and had to evict them, they damaged the apartments don't pay etc. This happened twice, so now if the gut says no, or there is guilty feeling or sympathy in our minds we won't rent it to that individual.
There are many other methods and opinions, this is just mine. Hope you find great tenants and have a wonderful time on this long prosperous journey