Managed to get this taken care of this evening. The rotary brush made things tremendously easier. I got better with the soldering as I went, but man, those d-pad contacts are brutally small. As suggested, once finished, I went over all the contacts with a hot glue gun. Well-invested $2.50. As you can see in the pic, I had some troubles with some of the solders, and even with some of the hot gluing, but I've tested them all, including the guide button, and all is well.
I hot-glued the trigger pots in the neutral position. I think I may order buttons for the right and left triggers, then put those together at a later time if I find a game that calls for them. Since they have their own soldering posts, it should be really easy to do. The RB/LB solders were the easiest of the bunch because of the posts.