I have always run around 8% for repairs and 8% for cap ex for my smaller multis and am curious if this stays consistent with properties in the 8-12 unit range?

Some owners will then accept the first application that fits their criteria and others may wait until a certain date and pick the strongest application from the pool of qualifying applicants.One important note is that the application criteria and process should be consistent for all applicants, whether it's regarding income requirements or past evictions.

Are there any agents that are having consistent success with listing expired's and fsbo's?

Parts of TX have consistent foundation issues.....clays that swell with heavy moisture.  

Sure it's more work, and takes more time, but the findings will certainly be more consistent than having 5 engineers on it.

In all the videos I've watched and the books I've read, I'm fairly consistently left with the feeling that there always something that they're not mentioning.

I'm assuming your retrofit consists of putting up plywood, holdowns, and clips to existing walls. 

Portfolio consists of 1/2 block comprising 4 upstair/downstair duplexes, a single family home and 8-plex.

Consistency is key.

A direct mail campaign will eventually get you the results you need but consistency is KEY when it comes to any form of marketing.