I didn't use the wires that came with the light, though they would have worked fine. Instead, I bumped the wiring up a notch from 18GA/105C to 16Ga/125C automotive wiring. I felt more comfortable with the larger gauge wire and more abrasion resistant insulation ('cause the OCP side of my brain told me to, that's why).

The Trailtech connector should work fine. Otherwise, you can get bullet terminals at RadioShack, Ace Hardware or any automotive store.

In terms of solder vs. crimping, I prefer soldered connections covered by heat-shrink tubing because they are less likely to fail in the field due to vibration, salt, dirt and general daily use. If you have the proper crimping tool, then crimping would work. I usually crimp, solder, then cover with heat-shrink tubing.